With short message service (SMS), you can send messages up to 160 characters. SMS of length more than 160 characters is broken down into smaller messages (where each message length can be up to 160 characters) and sent. When these SMS are received, the messages are combined and displayed as a single long message. The process of breaking down long SMS during sending and combining them while receiving is handled in the background.
Before you start the SDK instances you plan to use for SMS messages, make sure you have started NCF. See Simulating wireless connectivity between SDKs overview.
Java Developer’s Library (http://www.developer.nokia.com/document/Java_ME_Developers_Library/index.html)
Messaging information on Nokia Developer