Certificate common name did not match

I’m trying to set up TLS transport. In this case the client is a softphone (CSipSimple) on an Android phone that lives on an wireless providers network (in the DHCP address space of an autonomous network with no DNS registration) So, there is absolutely no way that I know of to create a client certificate with any kind of verifiable CN since the private IP is Dynamic, the public IP is random, and there is no way to register a client name in DNS.

This results in “Certificate common name did not match” because the code is comparing the IP address to the CN and they don’t match.

How can you setup TLS in such a case?