pjsip call hangup delayed if network switches from IPv6 to IPv4 during call

I am using PJSIP client for handling VOIP calls.currently i have two servers setup.

1 - test1.myvoipserver.com (only support IPv4)

2 - test2.myvoipserver.com (only support IPv6)

In client side, I am checking if user ip belongs to IPv4 family than I am routing call from test1.myvoipserver.com server which is supporting IPv4.

If user ip belongs to IPv6 family, I am routing call from test2.myvoipserver.com which is supporting only IPv6.

All calls are working fine except below scenario.

Scenario:

Let’s suppose user has two internet connections available.

4G - (Only on IPv6)

Wifi - (Only on IPv4)

User has made call on 4G, call was accepted by Party B and media packets are traveling fine. During the call user has started moving where Wifi is available his mobile internet automatically switches to Wifi. At that moment media packets will be loss which is understandable. I want to disconnect current call and made new call again with IPv4 server as Wifi is on IPv4.

Actual Result : On internet changes from IPv6 to IPv4 I forcefully disconnecting current call but call is not disconnected immediately on party A and B, it will disconnected after 2 minutes (probably when pjsip/server sends timeout).

Expected Result : Call should be disconnected immediately on both party A and party B

My Understanding : As my current call was on IPv6 server but new ip my device getting belongs to IPv4 and my current call server does not supporting IPv4 address so that’s why When sending Bye from client, server is not sending OK/ACK.

Note : Facing this issue is on PSTN Calls.

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