Historically caused by a firewall, or similar inspection or NAT device, in the network that is failing to parse specific messages used during call setup and call transfer.
Quick test - place 3 phones as close as possible, from a network perspective, to UCM and test. If working there then indicates in issue with the transit network. -Wes On Oct 8, 2014, at 9:38 AM, costas georgiou <ckos1...@hotmail.com<mailto:ckos1...@hotmail.com>> wrote: Hi All, I have an issue where apparently the phones (6921's) start to ring and someone picks them up and no one is there, they put the phone down and it keeps ringing. Also, on occassion, they go to transfer the phone and it gets cut off. Any ideas? REgards Cos _______________________________________________ cisco-voip mailing list cisco-voip@puck.nether.net<mailto:cisco-voip@puck.nether.net> https://puck.nether.net/mailman/listinfo/cisco-voip
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