Has anyone had any success doing this? Inbound calls work fine. Outbound calls have no audio in or out. Found this out today trying to configure a fax adapter at a client site. Fax adapter is configured as usual, with the exception of using an outbound proxy of the SBC IP address. Have tried using 3CX server LAN IP or FQDN for registration, no difference. For the purposes of a demonstration I configured a 2 port Cisco SPA112 analog adapter (officially unsupported by 3CX, but have had success using with other clients) with two extensions, Line 1 being a Fax extension, Line 2 being a regular 3CX extension, both using the SBC for an outbound proxy. I'm using a dumb analog phone for the purposes of the test, calling the same number. Note that there are zero packets/bytes received on the fax extension. Does anyone have any tips on a fix for this?