500 Internal Server Error with Keenetic Linear + Sky WiFi Italy + VoLTE

[nico.t_na]

Hi everyone,

I have an issue when trying to configure/use a Keenetic Titan (KN-1812) + Keenetic Linear with Sky Wifi (Italy) as ISP.

Thanks to another post in the forum, I was finally able to configure the telephone line properly, and apparently the main issue was with the SIP proxy, since the one provided in the official guide on how to use VoIP + a modem that's not the provided one (Sky Hub) seems to be wrong. The Sky website suggests voip.it.isp.sky, which causes a 503 error. While with voip.glb.it.isp.sky found here in the forum, and also being the default one for the predefined Sky profile, I'm able to make the telephone line almost work.

Only today, after an update , I wanted to test again the line and realized that I was not able to call my mobile phone, which is an Android with VoLTE enabled. After several attempts, I came to the conclusion that if VoLTE is disabled on my smartphone, I'm able to call from the home phone. If VoLTE is enabled, instead, it does not work and it looks like the number is busy.

I digged further, enabled additional logs on the Keenetic (related to the Phone Station component) and with VoLTE enabled, a 500 Internal Server Error is triggered at some point in the call.
I attach here some log files, with and without the VoLTE enabled on the mobile phone. I should have replaced all sensitive information, such as public IPv6, SIP username, and phone numbers.

Some info taken from the CLI:

show nvox sip-lines:
lines:
                 line:
                       id: 2
                     name: Sky (1)
                     code: 200
                   status: registered
              description: OK
                blacklist: empty, disabled
                whitelist: empty, disabled

(some) running-config:
sip 2
        name "Sky (1)"
        login <sip-username>
        password ns3 <password>
        domain voip.sky.it
        registration-uri voip.sky.it
        proxy voip.glb.it.isp.sky
        incoming-mask 1
        incoming-mask 2
        outgoing-mask 1
        outgoing-mask 2
        reg-timeout 3600
        keepalive 30
        disable-stun
        dtmf-mode inband
        transport udp
        audio-protocol rtp
        priority 2
        session-timer-mode disable
        session-timer 7200
        tls-security-mode sip-tls
        codec g711a
        codec g711u
    !

sip-common
        stun-server stun.l.google.com:19302
        agent "Keenetic Titan (KN-1812)"
        rtp-port 4000 through 4015
        udp-port 5060
        tcp-port 5060
        tls-port 5061
        100rel
    !

 

If you could help me it would be great
Thank you very much

VoLTE disabled.txt VoLTE enabled.txt