This problem seemed to happen recently but was likely causing issues before where the phone(s) do not ring.
Now there are a few reasons why this can happen especially if your adapter has DND mode enabled (disable it).
However that wasn't my issue and I only figured it out the other day when by fluke if you're on the phone (making a call) then calls will come in.
That's when I figured out the solution:
This likely applies to other adapters but in a Sipura/Linksys you'll find this under "Advanced" settings for your line.
|NAT Mapping Enable:
|NAT Keep Alive Enable:
Enable both of those especialy the Keep Alive as otherwise the PBX/Asterisk/server won't realize your phone is alive and ready to receive calls.
The above seems to have solved it for me.
What if the solution doesn't work or you have 2 lines active on your Linksys VOIP PAP2T?
This happened to me, at first the second line worked when enabling NAT Mapping and Keep Alive like above but then it stopped. The solution so far was to keep both lines using the same SIP port (5060) whereas the second line that stopped ringing was using 5061 (I changed it back to 5060).
I am not sure if it's an issue with my router or if it's only able to properly NAT VOIP on port 5060 but for now it is working.
I will try to report back in a few days if it is the final/working solution.
*This doesn't work so the solution was actually very short lived
My problem was solved by enabling NAT but it seemed something else wrong because the phone wouldn't ring. I had an old Sipura adapter using the same account that was still connecting and booting off the PAP2T! So no wonder nothing seemed to make it work. You shouldn't need to open any ports on your router either and mine works without that and wouldn't work with it.
So if you are upgrading from an old adapter make sure you disconnect and put it away to avoid hassle like mine!
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