The 2503-type telephone sets are standard desk sets similar to the 2500-type telephone sets. The 2503-type are used to provide Data-Phone service.

The sets are available as 2503C, 2503CM and 2503 CMW.

The telephone set has an exclusion key in place of the left plunger. As wired from the factory, lifting the handset will not cause the telephone to go "off-hook", but will allow you to monitor the line. Lifting the exclusion key causes the telephone to go "off-hook" and work like a standard 2500 telephone set.

These telephone sets are available in light gray (color code 61) only.

For more information, refer to Bell System Practice (BSP) Section 502-503-120.