Changing Caller Id for internal calls

[lsi]

I'm sure this is something simple that I'm just overlooking, but...

When we make an external call, the phone number we have designated with our VOIP provider is what goes out.

Is there a way to use a different number when we make a call (via extension) within the office? So we can tell which extension is calling us?

Thanks much!

 

[leejor]

I'm not sure if I have this clear. On an internal call, the calling extension number should be showing up on the called extensions display. What is the called party receiving? What type (make/models) set is it. Are they all behaving the same?