I have 2 VVX 601's that are set up on the same OSDM server. Phone 1 (version: 184.108.40.20689) tries to call internal extension Phone 2 (version: 220.127.116.1189). Phone 2 receives the incoming call, but once it answers it hangs up automatically. I can't determine which setting on the phone will allow these two phones to talk. All other samsung ip phones have no problem calling either of these phones.