Having a similar problem. All inbound calls are being directed straight to voicemail and when I try to call the missed number back off my freshphone account I am unable to.
So far they admitted having thrown out the ILBC codec that my router used.
From the Freshphone FAQ:
Audio codec =G729 alternatively iLBC or GSM
G729 is not too popular since there are/were license issues with it that could cost the router manufacturers.
The above listed codecs are very low bandwidth (and Quality!) being well under 20kBit/s but they save Freshphone a lot of traffic cost.
Unfortunately my router is more on the quality side of codecs (e.g. G711) and also the rare (in routers) OPUS as a new low bandwidth alternative is not implemented in my router.
The bandwidth cost is not the issue here. The problem is the massive increase of reports of bad call quality over iLBC because the issues with upgrading the mobile app and having to patch asterisk etc. We cant just set and forget, technology changes and we have to try our best to keep current. Even if you use a lovely codec like OPUS with its 44khz HD audio, our voice interconnect providers don't accept that codec, not even telkom accepts it. So while Freshphone to Freshphone will sound great and be OPUS native, any call in or out of our network will be trans coded to G729, unfortunately this isn't our choice, we have to adhere to the rules set down by our upstream provider.
Because we dont supply the quiptment, routers/phones etc, we try our very best to support as much as possible but there will be devices out there which we have never tested on, we dont know the codec support and so on. As far as I can see we dont even get Fritzboxes here so we are trying to help in the best we can, this is a free subscription service and we are offering as much support as we can.
With a new codec on Freshphone's side that my router can use the issue is solved.
I do not shed a tear for iLBC - gone for good.
Fast response, no fingerpointing, a pleasant support experience!