What type of module are the cordless phones plugged into? The phone should be capable of Caller ID - if connected to a 412 TDL or 024 TDL module. It may not show Caller ID if connected to an ETR module. The manual has no info on CLID - but the sales brochure claims that capability (perhaps only on an IP Office).
Since the 3910 partially emulates a TransTalk phone on the Magix system - (the TransTalk phones do show Caller ID) - CLID should work when connected a TDL module.
Tom Daugirdas,
President
STCG, Inc.
stcg.com