[OpenSIPS-Users] Further adventures in dual-stack ipv6/ipv4 questions

[Daniel Lakeland]

On 11/07/2017 09:22 AM, Daniel Lakeland wrote:
>
> This seems to be a major bottleneck for reliable calls over TLS via 
> WiFi. If the TLS connection can't be maintained because momentary WiFi 
> droppage causes reset packets to be sent by Android OS or other OS 
> then the registration is invalidated and the call will drop as soon as 
> the remote party tries to do anything (such as reINVITE or the like). 
> This will be true even though the RTP is traveling around just fine. 
> Is that more or less the sum of it?
>
> Are there things I could do to improve this situation? Suppose far end 
> wants to reINVITE either as a kind of pinging, or for a hold or 
> something. It sends SIP message to OpenSIPS, now over the last few 
> minutes OpenSIPS lost the specific registration from my client, and 
> then regained it when my client re-opened the connection. Is there a 
> way I can make OpenSIPS know what happened and forward my phone the 
> INVITE on the new socket? What things need to be supported on the 
> client? What needs configuration in the server?

It may help to know that I did the following test just now:

Bria 3.9.6.99409 on Android registered to OpenSIPS via ipv6 which then 
talks to Asterisk on same server.

Connect to OpenSIPS via Wifi using TLS on ipv6 only network, call 
asterisk to extension that reads the time for several minutes

While listening to the time, turn off Wifi entirely and wait about 4 
seconds... phone now switches to T-Mobile ipv6 mobile data network, 
magically audio returns after a few seconds.

Now, put phone into airplane mode, then turn on  just wifi.

Magically after several seconds, audio returns...

I didn't do packet captures etc, so I'm not sure what SIP messages were 
sent. But my guess is that when connection dropped, Bria was 
re-connecting, and then re-inviting the call to its new address. Bria is 
probably sending the Call-ID so the momentary losses of 
connections/registrations were OK for this call.

Now, if OpenSIPS had sent a ping, or the remote end had reINVITED during 
the period after I turned off wifi and before Bria got itself connected 
to OpenSIPS on the mobile network... or the like... I imagine I might 
have had a different experience.