This is a sage green Caller ID Sleekline Telephone made by Southwestern Bell, model FM2552SG.
The phone measures approximately 8.75" tall, 3.25" wide, 3.25" deep, 12.5" long for the cord, and 83.5" long for the phone cable.
The telephone is in good pre-owned condition in the original box. It has not been tested and is being sold as-is.