We are running into an issue with cisco SPA 112 and SPA 122 voip dialers where they will work perfectly fine for some phone providers but not for others.
To give a clearer picture on the issue, we are using these dialers with intercoms where someone will press a dial code on the intercom and it calls out to people where they will receive the call, be able to answer it, be able to speak with the person at the intercom, and they press a button on their phone to grant access to the door the intercom is at. A simple intercom solution.
Most phones and providers appear to work just fine (such as my samsung going through US Cellular). However, we noticed lately that some providers, such as verizon or AT&T, will not work through the dialer. A verizon phone will receive the call perfectly fine but cannot hear voice on the phone and any button responses (such as pressing 9 to allow access at the intercom) will not function. Additionally, if the verizon phone hangs up the call, the intercom still thinks the call exists because the verizon phone never sent a tone back saying the call ended. Its almost acting like its half duplex calling out through these providers. Again, other phones and providers work perfectly fine. We did rigorous testing where we found that other dialers work perfectly fine as well. We initially thought it was a cell provider issue but we setup a grandstream voip dialer using the same exact voip service, account, and everything as the cisco dialer and the grandstream was able to work fine with all phones. based on this, we narrowed it down to the cisco dialer itself. I understand its possible that verizon changed something on their end (possibly codecs they use) and made it stop working on the cisco dialer, but the fact it works on other dialers just fine means there is either a limitation to the cisco dialer where we can no longer use it or there is a setting that can be changed to resolve this. We tried changing the codecs/vocoder settings to test each one and none of them work.
If anyone could assist with this issue that would be great. we are on a time constraint which is why i wanted to call cisco and get support but they refuse to help without a service contract.
Thank you!
