Hi All, This weekend I just downloaded and installed the latest Debian ISO of 3Cx on an ESXi system of mine. So far everything appears to work except for one thing - incoming calls from PSTN I can make calls in between soft extensions, whether the extensions are behind the address translator or not. I can call out to the PSTN through the FXO gateway from soft extensions no problem. I just cannot receive inbound calls. The gateway is a Cisco 2600 with 4 voice FXO cards in it. The incoming POTS lines plug into that. Configs for the Cisco are from here: http://web.archive.org/web/20050212113924/http://www.tape.net/~gerry/asterisk/cisco26x0.html and here https://www.3cx.com/community/threads/3cx-and-cisco-router.20142/ and here https://www.voip-info.org/wiki-Asterisk+cisco+FXO Note that I have IOS 12.2, Cisco did not introduce userID authorization into SIP until IOS 12.4 One last thing: I would appreciate you not attempting to show your brilliance by telling me to get a different gateway. I am already aware of that "solution" It so happens that I had the hardware already and BEFORE I sink a lot of time and money into 3CX I'm willing to give it a try with what I have. If it does not work I can walk away from it now and write it off as just another OSS derivative product that has evolved into a turnkey system that isn't interoperable with anything anymore. I've already looked through the Linux command line and it seems plain that 3CX has changed all the configs so they can only be accessed by the web interface. So tricks like modifying sip.conf won't work. I suspect that if 3cx put a GENERIC entry for a regular SIP trunk in I could define 3 of them and point the Cisco to that and it would work. It seems plain that this configuration worked in the past with 3CX and it works with current asterisk. I'm quite willing to assume I have something wrong in the 3CX config. Thanks! I'll be happy to post configs/ router syslogs if anyone is interested.