Text messaging is a common feature of practically all communications protocols. In Telepathy it is done using text channels. See Section 6.5 ― Text Channels for a description of how to set up a text channel.
Telepathy provides two APIs for text messaging. The preferred API is the new Messages interface, which provides for rich-text messages, attachments and other messaging capabilities.
The second API is the simple interface. This API only supports plain text messages, and no advanced features like attachments and may be deprecated in the future.
Some connection managers do not currently support Messages. If your client needs to be compatible with older connection managers, it is advisable to implement both interfaces.