We have a Switchvox 310 with a total of about 30 phones at six different locations. Most of the phones are Digium, but there are about 10 Aastra phones. We are using WatchGuard Firewalls and Cisco Catalyst switches at most locations.
Over the past few months, we have had problems with phones becoming “UNREACHABLE” at all of the external locations. The phones at the location where the PBX sits do not have issues. After doing packet captures with tech support, we think that we have narrowed down what the problem is. The phones will register and then the PBX will send them their nonce password. The phones receive their password, but when they try to send it back, the packet is lost somewhere along the way. All of the correct ports are open to allow traffic, and we are not using SIP ALG or anything like that.
With the Aastra phones, I will manually get one registered, and then it will immediately knock another phone offline. The Digium phones will sometimes go into a “hollow” status and will not register even after a factory reset and being pointed to the configuration server. We have to take this phones to another network and then they register fine.
Does anybody have any idea what could be causing these issues? We are thinking that it might be a problem with our Cisco Catalyst switches. They were manufactured in about 2004~2005, and we think they might be a bit outdated. Any input would be much appreciated.