I would also like to hear your guy's opinions on the "digital-modulated cellphone sound" phenomenon. It sounds like some sort of machine voice or a really bad mp3. I hate when I get calls from people on cellphones and they sound like this. Is there a way to avoid it? Where does it come from? Are certain phones or services vulnerable to this?
I think that's related to how good of a signal you've got. I happened to me with Cingular, but I've never had it with T-Mo. When I'm talking to my fiancee on from a landline phone with her on our cell, I can't tell she's on a cell. My Nokia 3650's reception is that good.
Sorry Powerdoc, but in the last 6 months especially I've come to expect little from european Hi-Tech in general.
Anti-european bull. GSM is technologically much improved on most US mobile technologies. It was introduced more then 10 years ago and it simply works (almost around the globe).
Simply because we are at war with each other should not lead to badmouthing...
Anti-european bull. GSM is technologically much improved on most US mobile technologies. It was introduced more then 10 years ago and it simply works (almost around the globe).
Simply because we are at war with each other should not lead to badmouthing...
Do you know what you're talking about? I didn't think so. I'm an engineer, and generally speaking I applaud good technology wherever it comes from. Plus, there are plenty of things that "simply work."
1) Steam powered trains
2) Propeller driven airplanes
3) analog broadcast TV
4) GSM
There are also electric trains, jet airplanes, HDTV, and CDMA-derived cell networks that are much more advanced than their predecessors. Last time I checked, the US wasn't at war with Europe or France. European technology since the 80's or so just doesn't have a great track record. GSM is fine, but it's not really better than US TDMA based systems, which are woefully inferior to US and Asian CDMA based systems.
If you take the time to read the IS-95 spec (Verizon), it hits you how well thought out it is. It is clearly a cell network designed with the problems of GSM in mind, and maybe that's why 3G is an improved form of IS-95 and not GSM.
Technical jargon aside, I've found T-Mobile to be a pretty nice company. I don't hardly ever get dropped calls where I am, and their customer service has always been very good (at least for me -- my friend thinks otherwise).
I've known people who've had major signal and customer service problems with Sprint, and customer service problems with Cingular. The only two companies I've never heard much bad about are T-Mobile and Verizon.
I have a T610 and I'd recommend it - especially if you use iSync on a Mac. It was SOOOOOO nice to just sync all my contacts over to the phone when I got it instead of enter them in blocks of 5 through the web site.
Yep, but I actually have a (current) job in the tech sector as well. Even so, if I can tell you the technical reasons why one technology is better than another, I don't think a diploma matters too much in that respect.
as far as customer service is concerned, it may be worth noting that most firms these days outsource customer service to a handful of large, customer service companies. So experiences in customer service can be difficult to relate, especially if the firm changes it's service company.
Actually, GSM = most commonly used international standard = good.
CDMA is a superior technology in terms of QOS and data transmission, and providers currently using TDMA networks (GSM is a set of standards, and TDMA is part of that set) will transition to networks that use technology based on CDMA, but right now there is no good reason to pick a CDMA provider. The only conceivable future advantage is that they may be able to provide high-speed data services earlier than current GSM providers, but this headstart will only be by a matter or months.
The fact that 95% of the world uses GSM means that GSM providers benefit from economies of scale. This makes production of handsets and network gear cheaper, which means better coverage, cheaper service and better handsets (lighter, smaller, cheaper, better battery, wider choice) for GSM customers. GSM users can use the same phone when they travel, and can swap out a SIM card when they want a new handset taking all their data (and number) over without the need for any backend mucking about.
From a technological perspective, CDMA is better. In the real world, when both business and consumer perspectives are factored in, GSM is superior.
Actually, GSM = most commonly used international standard = good.
From a technological perspective, CDMA is better. In the real world, when both business and consumer perspectives are factored in, GSM is superior.
Interesting thought, but most of your "facts" are just plain wrong.
- Only Europe is GSM dominant. Asia and America use primarily CDMA based networks. 95% is way off. More like 50% on an optimistic day. That's partly why Nokia stock is going down the toilet.
-GSM providers will have to completely replace their entire cell backbone to go 3G. CDMA-standard providers will have it easier. This means the matter becomes more than jsut a few months lead.
Also consider that:
1) in America, Verizon has the most thorough network. I live in America, and I don't travel abroad with any frequency at all.
2) Versus all forms of TDMA (GSM included) IS-95, the American 2G CDMA standard, can hold more users per cell, offer greater range, provide better reception, and offer a million times greater security. Those translate into consumer preferences. A lot of people in America use Verizon for these reasons, at least indirectly.
3) GSM has more users than IS-95 worldwide, but with the fact that most of Asia uses CDMA based standards, I think consumer and business preference has strayed from GSM. As far as I can tell, the only reason why Europe insists on GSM is purely political.
4) You can say that paying $40,000 for a Ford Taurus is a better purchase than a much nicer Cadillac because more people own Ford Tauruses, but that reveals a level of mental retardation. There are enough people in the states (actually a plurality I believe) using IS-95 that there is no compatibility issue whatsoever. The only reason I can think of to buy a GSM service is if you want to have a Nokia or Ericsson phone, or if you use your phone in Europe. This used to be more of an issue, but a lot of Asian companies have stepped in and done a lot with IS-95 compatible phones.
5) My IS-95 phone also supports 3G CDMA. All IS-95 phones these days are Tri-mode. So when the transistion is made in my area, I won't have to buy another phone.
Sorry to rant so long, but I don't like it when people prolong the existence of obsolete technologies because they don't know better.
That's partly why Nokia stock is going down the toilet.
It is? Nokia had bad years in 2000 and 2001, but the stock looks like its been doing okay over the last quarter.
Quote:
GSM providers will have to completely replace their entire cell backbone to go 3G. CDMA-standard providers will have it easier. This means the matter becomes more than jsut a few months lead.
Providers that opted for the IS-95 standard and implemented CDMAOne networks generally now have CDMA2000 1xRRT networks in place. The next step will probably be CDMA2000 1xEV-DO (data only, so not for phones, but useful in making the transition.), followed by CDMA2000 1xEV-DV (data and voice) and then CDMA2000 3x.
Providers that initially elected to use GSM networks generally now have GSM/GPRS networks in place. The next step for most will likely be EDGE networks (AT&T just launched theirs), followed by W-CDMA.
Neither CDMA2000 1xRRT nor GSM/GPRS, despite what marketing brochures might say, are 3G. While EDGE is a step closer to 3G, it is still not fully there. CDMA2000 1x EV-DV, CDMA2000 3x and W-CDMA are all considered true 3G. No provider has yet to launch true 3G services in the US.
Each one of these transitions, no matter what the underlying technology, requires hardware, channel card and software upgrades to the network infrastructure. The reason why the GSM providers have more work ahead of them is that the transition from GSM/GPRS or EDGE to W-CDMA is a more radical one than the transition from CDMA20001xRRT to CDMA2000 1xEV-DO / DV?and a more expensive one?but it has been done before.
Quote:
in America, Verizon has the most thorough network. I live in America, and I don't travel abroad with any frequency at all.
I live in America, and I travel abroad quite a bit. It is nice to be able to use my phone when I do. Everyone I know from Europe can use theirs when they come here (or pretty much anywhere else for that matter). Being limited to the US would be a big minus for me.
Quote:
Versus all forms of TDMA (GSM included) IS-95, the American 2G CDMA standard, can hold more users per cell, offer greater range, provide better reception, and offer a million times greater security.
You are correct in stating that CDMA networks can hold more users per cell and offer greater range, but reception and security are comparable.
Quote:
GSM has more users than IS-95 worldwide, but with the fact that most of Asia uses CDMA based standards, I think consumer and business preference has strayed from GSM.
Most of Asia does not use CDMA based standards. China, Japan and Korea do all have CDMA providers, but the only market where CDMA dominates is Korea. Of more than 200 million cellular subscribers in China, 9 million use CDMA. Of approximately 90 million cellular subscribers in Japan, 17 million use CDMA. GSM is proving to be much more popular with Telecos in Latin America as well
Quote:
As far as I can tell, the only reason why Europe insists on GSM is purely political.
Then you need to learn more about why the standard was implemented. CDMA was not regarded as being usable at the time. Qualcomm later managed to make it work but GSM was already in use by that point. That GSM is an open standard is also an plus. Why do you think AT&T, T-Mobile and Cingular in the US all 'insist' on using it?
Quote:
4) You can say that paying $40,000 for a Ford Taurus is a better purchase than a much nicer Cadillac because more people own Ford Tauruses, but that reveals a level of mental retardation.
How about the level of mental retardation that is revealed by the use of poorly articulated analogies that make absolutely no sense?
Quote:
There are enough people in the states (actually a plurality I believe) using IS-95 that there is no compatibility issue whatsoever. The only reason I can think of to buy a GSM service is if you want to have a Nokia or Ericsson phone, or if you use your phone in Europe. This used to be more of an issue, but a lot of Asian companies have stepped in and done a lot with IS-95 compatible phones.
Such as?
Quote:
5) My IS-95 phone also supports 3G CDMA. All IS-95 phones these days are Tri-mode. So when the transistion is made in my area, I won't have to buy another phone.
I hate to break it to you, but 'tri-mode' refers to the fact that such phones operate on the 800MHz analog band, the 900MHz CDMA band and the 1900MHz CDMA band. It has nothing to do with 3G. When 3G networks are rolled out by Verizon, any consumer who wishes to take advantage of 3G services will need a new handset. You will be able to hold on to your current phone for voice, but GSM providers will most likely overlay their networks to provide the same services during transition.
Quote:
Sorry to rant so long, but I don't like it when people prolong the existence of obsolete technologies because they don't know better.
I am not advocating providers that use GSM networks because I believe GSM to be a superior technology (which is something I stated in my earlier post). I am advocating them because there are advantages to being able to use your phone in 95% of the world, because a wide range of better handsets with better features is available for GSM networks and because GSM provides consumers with greater mobility between providers.
As for your comment about people who "don?t know better"...I think the statement you made regarding your tri-mode phone says everything that needs to be said. I?d also love to see a source for your assertion that CDMA security being "a million times greater", by the way.
OK, no purpose arguing with someone who continues to be incorrect, so I'll leave it up to you to find out why all of your claims are, still, incorrect.
In an ideal world, IS-95 and GSM have the same resilience to noise, but GSM offers no multipath capabilities, and reception is worse. Google it. Also go ahead and google CDMA vs. GSM security or something. There's a reason why the military uses something similar to CDMA.
And my phone has a sticker on it. . . it says "Qualcomm 3G CDMA." On the box it says "Trimode CDMA." The American 3G band is indeed at 1.9Ghz, and Sprint does indeed have a 3G CDMA system in America, though it's limited to a great extent. Go Figure.
Sorry to be a complete asshole, but please, don't argue about things you don't understand. I'm no expert, but I can probably tell you more than you want to know about the ins and outs of cellular telephony.
OK, no purpose arguing with someone who continues to be incorrect, so I'll leave it up to you to find out why all of your claims are, still, incorrect.
How about just backing your assertions up with something...
Scroll halfway down the page on the second link you provided, then check out the link entitled "95% of countries use GSM."
Quote:
In an ideal world, IS-95 and GSM have the same resilience to noise, but GSM offers no multipath capabilities, and reception is worse. Google it. Also go ahead and google CDMA vs. GSM security or something. There's a reason why the military uses something similar to CDMA.
I should find some sources that prove you right? Don't be so lazy.
Quote:
And my phone has a sticker on it. . . it says "Qualcomm 3G CDMA." On the box it says "Trimode CDMA." The American 3G band is indeed at 1.9Ghz, and Sprint does indeed have a 3G CDMA system in America, though it's limited to a great extent. Go Figure.
Go and learn something about the ITU IMT-2000 standard. Then find out what the current range of data services available in the US today are. Sprint may refer to CDMA2000 1xRTT as '3G' but it still falls outside the definition of 3G.
I won't bother trying to explain what tri-mode actually means to you again.
Quote:
Sorry to be a complete asshole
That's okay.
Quote:
don't argue about things you don't understand.
Don't worry, I won't.
Quote:
I'm no expert
That's certainly true.
Quote:
I can probably tell you more than you want to know about the ins and outs of cellular telephony.
I sincerely doubt it, particularly since the extent of your knowledge appears to be what you read on the side of the box your phone came in.
Comments
Originally posted by Randycat99
I would also like to hear your guy's opinions on the "digital-modulated cellphone sound" phenomenon. It sounds like some sort of machine voice or a really bad mp3. I hate when I get calls from people on cellphones and they sound like this. Is there a way to avoid it? Where does it come from? Are certain phones or services vulnerable to this?
I think that's related to how good of a signal you've got. I happened to me with Cingular, but I've never had it with T-Mo. When I'm talking to my fiancee on from a landline phone with her on our cell, I can't tell she's on a cell. My Nokia 3650's reception is that good.
Originally posted by Splinemodel
TMobile = GSM = French technology = crap.
Sorry Powerdoc, but in the last 6 months especially I've come to expect little from european Hi-Tech in general.
Anti-european bull. GSM is technologically much improved on most US mobile technologies. It was introduced more then 10 years ago and it simply works (almost around the globe).
Simply because we are at war with each other should not lead to badmouthing...
Originally posted by Smircle
Anti-european bull. GSM is technologically much improved on most US mobile technologies. It was introduced more then 10 years ago and it simply works (almost around the globe).
Simply because we are at war with each other should not lead to badmouthing...
Do you know what you're talking about? I didn't think so. I'm an engineer, and generally speaking I applaud good technology wherever it comes from. Plus, there are plenty of things that "simply work."
1) Steam powered trains
2) Propeller driven airplanes
3) analog broadcast TV
4) GSM
There are also electric trains, jet airplanes, HDTV, and CDMA-derived cell networks that are much more advanced than their predecessors. Last time I checked, the US wasn't at war with Europe or France. European technology since the 80's or so just doesn't have a great track record. GSM is fine, but it's not really better than US TDMA based systems, which are woefully inferior to US and Asian CDMA based systems.
If you take the time to read the IS-95 spec (Verizon), it hits you how well thought out it is. It is clearly a cell network designed with the problems of GSM in mind, and maybe that's why 3G is an improved form of IS-95 and not GSM.
Originally posted by Splinemodel
I didn't think so. I'm an engineer <snip>
I thought you were still in school.
I've known people who've had major signal and customer service problems with Sprint, and customer service problems with Cingular. The only two companies I've never heard much bad about are T-Mobile and Verizon.
I have a T610 and I'd recommend it - especially if you use iSync on a Mac. It was SOOOOOO nice to just sync all my contacts over to the phone when I got it instead of enter them in blocks of 5 through the web site.
Originally posted by pensieve
I thought you were still in school.
Yep, but I actually have a (current) job in the tech sector as well. Even so, if I can tell you the technical reasons why one technology is better than another, I don't think a diploma matters too much in that respect.
as far as customer service is concerned, it may be worth noting that most firms these days outsource customer service to a handful of large, customer service companies. So experiences in customer service can be difficult to relate, especially if the firm changes it's service company.
Originally posted by Splinemodel
GSM = French technology = crap.
Actually, GSM = most commonly used international standard = good.
CDMA is a superior technology in terms of QOS and data transmission, and providers currently using TDMA networks (GSM is a set of standards, and TDMA is part of that set) will transition to networks that use technology based on CDMA, but right now there is no good reason to pick a CDMA provider. The only conceivable future advantage is that they may be able to provide high-speed data services earlier than current GSM providers, but this headstart will only be by a matter or months.
The fact that 95% of the world uses GSM means that GSM providers benefit from economies of scale. This makes production of handsets and network gear cheaper, which means better coverage, cheaper service and better handsets (lighter, smaller, cheaper, better battery, wider choice) for GSM customers. GSM users can use the same phone when they travel, and can swap out a SIM card when they want a new handset taking all their data (and number) over without the need for any backend mucking about.
From a technological perspective, CDMA is better. In the real world, when both business and consumer perspectives are factored in, GSM is superior.
Originally posted by kneelbeforezod
Actually, GSM = most commonly used international standard = good.
From a technological perspective, CDMA is better. In the real world, when both business and consumer perspectives are factored in, GSM is superior.
Interesting thought, but most of your "facts" are just plain wrong.
- Only Europe is GSM dominant. Asia and America use primarily CDMA based networks. 95% is way off. More like 50% on an optimistic day. That's partly why Nokia stock is going down the toilet.
-GSM providers will have to completely replace their entire cell backbone to go 3G. CDMA-standard providers will have it easier. This means the matter becomes more than jsut a few months lead.
Also consider that:
1) in America, Verizon has the most thorough network. I live in America, and I don't travel abroad with any frequency at all.
2) Versus all forms of TDMA (GSM included) IS-95, the American 2G CDMA standard, can hold more users per cell, offer greater range, provide better reception, and offer a million times greater security. Those translate into consumer preferences. A lot of people in America use Verizon for these reasons, at least indirectly.
3) GSM has more users than IS-95 worldwide, but with the fact that most of Asia uses CDMA based standards, I think consumer and business preference has strayed from GSM. As far as I can tell, the only reason why Europe insists on GSM is purely political.
4) You can say that paying $40,000 for a Ford Taurus is a better purchase than a much nicer Cadillac because more people own Ford Tauruses, but that reveals a level of mental retardation. There are enough people in the states (actually a plurality I believe) using IS-95 that there is no compatibility issue whatsoever. The only reason I can think of to buy a GSM service is if you want to have a Nokia or Ericsson phone, or if you use your phone in Europe. This used to be more of an issue, but a lot of Asian companies have stepped in and done a lot with IS-95 compatible phones.
5) My IS-95 phone also supports 3G CDMA. All IS-95 phones these days are Tri-mode. So when the transistion is made in my area, I won't have to buy another phone.
Sorry to rant so long, but I don't like it when people prolong the existence of obsolete technologies because they don't know better.
Originally posted by Splinemodel
Interesting thought, but most of your "facts" are just plain wrong...
I can provide sources if you like:
95% of the world uses GSM.
GSM providers benefit from economies of scale.
That's partly why Nokia stock is going down the toilet.
It is? Nokia had bad years in 2000 and 2001, but the stock looks like its been doing okay over the last quarter.
GSM providers will have to completely replace their entire cell backbone to go 3G. CDMA-standard providers will have it easier. This means the matter becomes more than jsut a few months lead.
Providers that opted for the IS-95 standard and implemented CDMAOne networks generally now have CDMA2000 1xRRT networks in place. The next step will probably be CDMA2000 1xEV-DO (data only, so not for phones, but useful in making the transition.), followed by CDMA2000 1xEV-DV (data and voice) and then CDMA2000 3x.
Providers that initially elected to use GSM networks generally now have GSM/GPRS networks in place. The next step for most will likely be EDGE networks (AT&T just launched theirs), followed by W-CDMA.
Neither CDMA2000 1xRRT nor GSM/GPRS, despite what marketing brochures might say, are 3G. While EDGE is a step closer to 3G, it is still not fully there. CDMA2000 1x EV-DV, CDMA2000 3x and W-CDMA are all considered true 3G. No provider has yet to launch true 3G services in the US.
Each one of these transitions, no matter what the underlying technology, requires hardware, channel card and software upgrades to the network infrastructure. The reason why the GSM providers have more work ahead of them is that the transition from GSM/GPRS or EDGE to W-CDMA is a more radical one than the transition from CDMA20001xRRT to CDMA2000 1xEV-DO / DV?and a more expensive one?but it has been done before.
in America, Verizon has the most thorough network. I live in America, and I don't travel abroad with any frequency at all.
I live in America, and I travel abroad quite a bit. It is nice to be able to use my phone when I do. Everyone I know from Europe can use theirs when they come here (or pretty much anywhere else for that matter). Being limited to the US would be a big minus for me.
Versus all forms of TDMA (GSM included) IS-95, the American 2G CDMA standard, can hold more users per cell, offer greater range, provide better reception, and offer a million times greater security.
You are correct in stating that CDMA networks can hold more users per cell and offer greater range, but reception and security are comparable.
GSM has more users than IS-95 worldwide, but with the fact that most of Asia uses CDMA based standards, I think consumer and business preference has strayed from GSM.
Most of Asia does not use CDMA based standards. China, Japan and Korea do all have CDMA providers, but the only market where CDMA dominates is Korea. Of more than 200 million cellular subscribers in China, 9 million use CDMA. Of approximately 90 million cellular subscribers in Japan, 17 million use CDMA. GSM is proving to be much more popular with Telecos in Latin America as well
As far as I can tell, the only reason why Europe insists on GSM is purely political.
Then you need to learn more about why the standard was implemented. CDMA was not regarded as being usable at the time. Qualcomm later managed to make it work but GSM was already in use by that point. That GSM is an open standard is also an plus. Why do you think AT&T, T-Mobile and Cingular in the US all 'insist' on using it?
4) You can say that paying $40,000 for a Ford Taurus is a better purchase than a much nicer Cadillac because more people own Ford Tauruses, but that reveals a level of mental retardation.
How about the level of mental retardation that is revealed by the use of poorly articulated analogies that make absolutely no sense?
There are enough people in the states (actually a plurality I believe) using IS-95 that there is no compatibility issue whatsoever. The only reason I can think of to buy a GSM service is if you want to have a Nokia or Ericsson phone, or if you use your phone in Europe. This used to be more of an issue, but a lot of Asian companies have stepped in and done a lot with IS-95 compatible phones.
Such as?
5) My IS-95 phone also supports 3G CDMA. All IS-95 phones these days are Tri-mode. So when the transistion is made in my area, I won't have to buy another phone.
I hate to break it to you, but 'tri-mode' refers to the fact that such phones operate on the 800MHz analog band, the 900MHz CDMA band and the 1900MHz CDMA band. It has nothing to do with 3G. When 3G networks are rolled out by Verizon, any consumer who wishes to take advantage of 3G services will need a new handset. You will be able to hold on to your current phone for voice, but GSM providers will most likely overlay their networks to provide the same services during transition.
Sorry to rant so long, but I don't like it when people prolong the existence of obsolete technologies because they don't know better.
I am not advocating providers that use GSM networks because I believe GSM to be a superior technology (which is something I stated in my earlier post). I am advocating them because there are advantages to being able to use your phone in 95% of the world, because a wide range of better handsets with better features is available for GSM networks and because GSM provides consumers with greater mobility between providers.
As for your comment about people who "don?t know better"...I think the statement you made regarding your tri-mode phone says everything that needs to be said. I?d also love to see a source for your assertion that CDMA security being "a million times greater", by the way.
Originally posted by CosmoNut
Come on. You guys are both pretty.
Aw shucks
The 95% mark is dead wrong
http://www.cdg.org/news/press/2003/nov18_03.asp
http://www.cellular.co.za/stats/stats-main.htm
In an ideal world, IS-95 and GSM have the same resilience to noise, but GSM offers no multipath capabilities, and reception is worse. Google it. Also go ahead and google CDMA vs. GSM security or something. There's a reason why the military uses something similar to CDMA.
And my phone has a sticker on it. . . it says "Qualcomm 3G CDMA." On the box it says "Trimode CDMA." The American 3G band is indeed at 1.9Ghz, and Sprint does indeed have a 3G CDMA system in America, though it's limited to a great extent. Go Figure.
Sorry to be a complete asshole, but please, don't argue about things you don't understand. I'm no expert, but I can probably tell you more than you want to know about the ins and outs of cellular telephony.
Originally posted by Splinemodel
OK, no purpose arguing with someone who continues to be incorrect, so I'll leave it up to you to find out why all of your claims are, still, incorrect.
How about just backing your assertions up with something...
Quote:
The 95% mark is dead wrong
http://www.cdg.org/news/press/2003/nov18_03.asp
http://www.cellular.co.za/stats/stats-main.htm
Scroll halfway down the page on the second link you provided, then check out the link entitled "95% of countries use GSM."
Quote:
In an ideal world, IS-95 and GSM have the same resilience to noise, but GSM offers no multipath capabilities, and reception is worse. Google it. Also go ahead and google CDMA vs. GSM security or something. There's a reason why the military uses something similar to CDMA.
I should find some sources that prove you right? Don't be so lazy.
Quote:
And my phone has a sticker on it. . . it says "Qualcomm 3G CDMA." On the box it says "Trimode CDMA." The American 3G band is indeed at 1.9Ghz, and Sprint does indeed have a 3G CDMA system in America, though it's limited to a great extent. Go Figure.
Go and learn something about the ITU IMT-2000 standard. Then find out what the current range of data services available in the US today are. Sprint may refer to CDMA2000 1xRTT as '3G' but it still falls outside the definition of 3G.
I won't bother trying to explain what tri-mode actually means to you again.
Quote:
Sorry to be a complete asshole
That's okay.
Quote:
don't argue about things you don't understand.
Don't worry, I won't.
Quote:
I'm no expert
That's certainly true.
Quote:
I can probably tell you more than you want to know about the ins and outs of cellular telephony.
I sincerely doubt it, particularly since the extent of your knowledge appears to be what you read on the side of the box your phone came in.