What is the compatibility of Alcatel IP Telephony over Cisco infrastructure? What edge would Cisco have over Alcatel?
Another advantage is that you already know your Cisco gear which means the transfer of knowledge would take less time on the Cisco gear than with Alcatel. Although, I have to say the Alcatel solution is also very good.
I would suggest that you create a score card - include features, maintenance costs, warranty periods, training times, ease for moves, adds and changes, availability of local support, backup power options in the event of a power loss, E-911 capabilities, interoperability with other equipment, how they address analog lines, etc. Evaluating the critical things will help you with your decision.
This was first published in March 2006