OpenSIPS configuration

Using OpenSIPS version 3.1 I would like a configuration file with the following details Mid-Registrar for multiple domains/realms (in-memory) to Primary Freeswitch Server (UDP/TLS) with Failover to Secondary Freeswitch Server Calls from carrier proxied to Freeswitch Server with Failover to Secondary Freeswitch Server Calls from UA are proxied to Freeswitch Server with Failover to Secondary Freeswitch Server Presence should also be proxied. MWI and Park presence need to be handled. NAT must be handled. I would like to set an alias tag to any contact header proxied by mid-register in the form, ;alias={contact_public_ip}~{port} I'd like to avoid using a database if possible. Not a deal-breaker, but I would prefer to run in memory. Project completed with a working OpenSIPS Configuration file. Testing will be necessary.