No problem with IPV4 for years. Changed Yealink and Bria phones to IPV6, they still work fine including getting VM. But with IPV6 FS only sends a NOTIFY 1 out of ten times so the phones don't set MWI. A sip trace during registration shows everything identical between MWI and non-MWI working except that when MWI does work a NOTIFY is sent to the phone. The NOTIFY, and only the NOTIFY, references IPV4 addresses in “From, To, Message-Account” and I wonder if that may be the cause. I tried to change Message-Account to IPV6 but it gets truncated at the first colon, I opened jira FS-9428 for that. I am wondering if this problem is one for Jira too or a config issue? Anyone run into this or have a suggestion? Thanks.

Mario G