IPv4 and IPv6 for SipTransport.ContactHost

[sipsorcery]

I am very inspired by this issue, my program is also deployed in K8s, using Loadbalancer to provide external services, I am now encountering a new problem, I need to support both IPv4 and IPv6, but SipTransport.ContactHost only supports setting one value, is there any other way? Thanks

Originally posted by @Forfires in #1413

[sipsorcery]

@Forfires the easiest way would be to use a hostname instead of an IP address. You could set up your hostname with IPv4 and IPv6 addresses.

Apart from that there is currently no way to support to IP addresses for the default ContactHost. An enhancement would be needed to support both and add the logic to set appropriately.