Originally Posted by solipsism Wikipedia's SMS page
sides with Amorya's comments, but empirical testing to and from a couple of cell phones will bring certainty to the debate.
Larger content (known as "long SMS" or "concatenated SMS") can be sent segmented over multiple messages, in which case each message will start with a user data header (UDH) containing segmentation information. Since UDH is inside the payload, the number of characters per segment is lower: 153 for 7-bit encoding, 134 for 8-bit encoding and 67 for 16-bit encoding. The receiving handset is then responsible for reassembling the message and presenting it to the user as one long message. While the standard theoretically permits up to 255 segments, 6 to 8 segment messages are the practical maximum, and long messages are often billed as equivalent to multiple SMS messages.
The entry only explains that the 'receiving handset' is responsible for reassembling the messages. It doesn't state that all
receiving handsets are required to (and can) reassemble the messages. It also doesn't state that 'Long SMS' is a requirement on a phone. Granted, the majority of the phones which I've owned have allowed the generation of Long SMS messages. I can reasonably state that a smaller percentage of the phones that I have owned will reassemble Long SMS messages that were sent to me. (This may also be network dependent, in some cases, as a function of the SMSC that is being used.)
If you read one paragraph up on the Wikipedia entry, it's stated that the SMS limit is 160 characters (using a Western character encoding).
I don't see how this differs to my original post.
Surely someone has a iPhone and doesn't mind spending half-a-dollar on a bit of testing with me.