I have about 10 IP phones sitting behind a mtik493AH. Every week or two the phones loose registration with the server and I must reboot the mtik to re-establish. Simply rebooting the phones does not work. I also noticed just recently, due to my researching the cause of this issue, when looking under firewall > connections I see a ton of “U” for udp connections. I am assuming this is part of my problem but not sure how to resolve. I have increased my UDP timeouts in hopes of resolving but no success. I also was reading that I should disable SIP helper? Any assistance is greatly appreciated.
I too had this issue with a RB 493AH, but only 2 IP Phones. Cisco 9971’s With the ROS as the TFTP server giving out the config file. No CUCM. ( Took Long time to get a working xml file for the 9900 series phone… MONTHS)
Anyways, the issue creeped up slowly, some days worse then others. I contacted the VoIP provider, voip.ms, they see that the registrations were timing out too.
I suspected the 493AH as well, but then I relized that this loss of connection was on every device at random times, but only during “peak usage” 8 - 11 pm.
Turns out that my ISP, Shaw Cable has such high ping times during this, and the timeouts were caused by this. Naturally, I bitched to them, they said they had a node split planned, and they did a few other things that they didn’t tell me on my connection. Ever since this day, I have not had timeouts on the voip phones.
One thing to ask, are you using different sip ports for each of your sip devices? And I have the sip helper OFF as well.
Are the disconnects corresponding with your Internet dropping or the Internet PPPoE having to reconnect?
Do you have ADSL router providing internet connection?