Hmmm.... well I have 2 different part numbers for the 24 button ETW phones, there is a 24 button standard phone ETW-24DD-1 and a 24 button speaker display ETW-24DS-1.

So the question is, will either of these phones work on an NEC Electra system currently running some 16 button display ETW-16DC-1's?

Is there any way to find out exactly what information I need about the customer's Electra system to verify these phones are compatible (not sure if they know the version number, and installer is out of the picture)?