What does milliwatt do? reorder_route_req:55(<0.10740.256>) sending response: 686 PICNIC milliwatt_route_req:35(<0.10747.256>) milliwatt does not know what to do with this!

So, I can see that user is registered and can make a calls. but issue with incoming calls, I run sngrep and I see │SIP/2.0 410 Not registered when call coming to the system

there is definitely some issue with firewall on the client side. Is there any specific parameters need to be configured for inbound calls?

SmartPBX showing error: NUMBER_CHANGED

mentax_: if client firewall issues, check for SIP ALG and disable, or move them to port 7000 (often ALG looks at 5060 traffic only)

or TLS

mc_ they are on port 7000. I tried to run SIP-ALG tester and it said that there is no ALG. Other phones running with VPN and kinda work. But without VPN it works 1 time out of 15

incoming calls is failing to voicemail, outgoing calls work as expected

and the client has this issue with previous couple carriers. Trying to figure out what is the root issue of that

I tried 3 different brand phones: Polycom, Snom, Grandstream... Same issue with all off them =(

is there anything else I can try?

mentax_: replace their gateway with new hardware??

get a new ISP??

they use spectrum and it's work fine. The bigger issue is very strict rules on their network.

same phone works just fine in other location

does sngrep showing keep-alive requests?

mc_ I wonder iff keep-alive interval of 30 seconds will do the magic

yeah, see what the firewall is configured for NAT mapping timeouts

typically 300s is a recommended lowest expiration

but you can get OPTIONS from kamailio to the device to keep the NAT hole open

so, 30s is too small?

depends on your client's firewall's settings

by default poly has keep-alive disabled...

I turn it on and set to 360s, look like it fixed the issue