A standard text message can contain up to 160 characters. With toText.net it’s possible to concatenate messages together so that longer ones can be sent, but in priciple the 160 characters is what most people consider to be a text message.
One problem with the 160 characters though is that it assumes that the sender is only using ‘English’ characters – see http://www.developershome.com/sms/gsmAlphabet.asp for a list of the supported alphabet. Therefore, people wishing to use east european or asian character sets, for example, have been largley unsupported.
The good news is that with toText.net we have full support for virtually all characters. For the techies amongst you, we can encode all text messages as UTF-8, which means we can send almost anything. The slight downside is that the number of characters in a message drops from 160 to 70, but it’s still possible for us to join texts together as usual.