In general you do not require Sip inspection enabled on traffic flowing via VPN, as we do not require dynamic pinhole to be opened and not nat is required at layer-7. I would suggest disable SIP inspection for this specific host and then try connecting.
So go ahead and disable inspection for traffic coming via VPN tunnel.
access-list test extended deny ip 172.16.10.0 255.255.255.0 172.17.10.0 255.255.255.0
access-list test extended deny ip 172.17.10.0 255.255.255.0 172.16.10.0 255.255.255.0
access-list test extended permit ip any any
(make sure you have permit ip any any) at last to allow rest of the traffic for inspection.
match access-list test
We have configured the outside and inside Interface with official ipv6 adresses, set a default route on outside Interface to our router, we also have definied a rule , which also gets hits, to permit tcp from inside Interface to any6.
In Syslog I also se...