The limit for SMS messages is 160 characters: Sending larger messages is possible, but the host and receiver both need to be capable of 8-bit messages (which is most likely). The long message is then sent using 2 or more SMS messages, with the only difference being that each one contains a small header indicating its part of a longer message.
There are a number of phone-related apps (Mphone, etc) which should be able to send extended information iirc.
