I know an SBC would be the BEST solution but until the client has the budge, is it possible to interconnect multiple sites each using a different SIP port.
main site SIP 5060
remote site 1 SIP 5062
remote site 2 SIP 5068
PJSIP is available but also on non-standard ports. Can you specify the port to use in the SIP-TRUNK settings page?
The main site has various ITSP’s all talking on 5060 so they don’t want to change the main and don’t want to use standard ports on all the cloud PBX’s serving the remote users.