On the bigger ones, I probably will look towards SBC. Problem with remote clients so far is they tend to not have an IT person, so I'm trying to limit equipment that needs managed at the remote sites. I don't have control over their network, just remote guidance. Remote STUN has worked well so far with existing clients. Going forward, I'm trying to compile suggested routers for these smaller offices that I can recommend to them to purchase on their own that will not have issues with voip. Since we're recording all calls for them, keeping local LAN audio local isn't a concern. Bigger clients tend to have IT person and also use a more robust router like an ASA which is handling the STUN extensions just fine.
But as far as SBC goes, knowing that I don't have direct remote access to their network, and limited help on their end, what is the best implementation for this type of client, lets say 5-20 extensions? PI, Windows workstation? I guess with Windows, it would be easy to set up remote access if they allowed. What is the ongoing maintenance of an SBC going to be, i.e. how often does 3CX have updates that will need applied? Also, I know I'll gain some capabilities, but seems like when I did test it a while back, MAKECALL did not work with 3CX client at the remote site or via RDP to a remote server elsewhere and the phone on the remote LAN behind the SBC. My clients use custom CRM local or hosted and we use MAKECALL, Windows API, and 3CX client CTI to get them click to call functionality.