My customer has a Cisco IP voice/data network and they would be interested in the ES400 if it can perform well as a VoWLAN phone. The obvious advantage is that the ES400 can do more than just be a VoWLAN phone ie. run the branch stock management application.   Does anyone have any suggestions/recommendations of a suitable soft phone client that will allow the ES400 to run work just like a Cisco wireless phone? I assume the protocol is SIP but have requested more information. Any one out there with customers using ES400 on a Cisco voice network? Would like to hear about the experience good or bad and what is supported and what is missing compared to a native Cisco IP phone. rgds,