SIP protocol thru 2nd gateway

[Gautier]

Hi,

I have SIP phone on OVH with the sbc6.fr.sip.ovh domain. But where I actually live I cannot access to this domain.
Until now I use SIP phone connected to my router with redirection to another router in France via wireguard and everything was ok.
But this phone die and I would like to use softphone without redirect full ip flow but just the SIP.

If I use openvpn to connect to the router in France, I get my connection.

How should I do?