In FreePBX13 I could create an extension with pjsip and set the max extensions to 5. This would create a corresponding number of VPN clients… which I could then pick and choose from in EPM. AND IT WORKED until the commercial sysadmin decided to disable itself.
In FreePBX14 I can create an extension with pjsip and max-clients=5, however, only one vpn client. Initially I assigned the same vpn client to each of my phones, however, since openvpn was not configured to share a configuration only one phone worked and was likely to be disconnected before the call finished.
The second problem… I manually created vpn clients for my phones… and that worked for a while. However, spontaneously my vpn clients were reassigned all over the place and to different phones.