Text messaging is disabled by default and doesn't appear in the Message screen unless enabled, and can only be enabled on One Talk lines that don't have a smartphone as a primary device.

If two desk phones are configured on the same line, messages are delivered to only one of the desk phones. It's recommended to enable the text messaging feature on only one desk phone per line.

If a line is being shared by a desk phone and other endpoints (e.g., Mobile App, Desktop app), all endpoints receive incoming messages. However, messages sent from a desk phone won't appear as outgoing messages on the other endpoints.

Desk phones only support SMS; MMS isn't supported. If a picture / video message is sent to a desk phone line, any media in the message is removed and only the accompanying text displays.

The desk phone can store up to 50 text messages across all folders. When the phone reaches 50 messages, the user is notified that the mailbox is full and messages should be deleted. If the user does nothing, when a new message is received the oldest message is deleted automatically.

Maximum character count per message is 500 for T53W and T54W models, and 918 for T57W models. Once the maximum character count is reached, any additional text is truncated.