Weird incoming calls problem

[evilmonkey]

Hi,

Just wondering if anyone else experiences this: people who call me recently started complaining that they're sporadically getting a busy tone when they call me. Alternatively, they complain that it just rings forever. Normally when this happens to someone, if they try to hang up and call back right away, it would happen again. The only solution seems to be to wait an hour or two and try again then. This seems to have started after the weekend of downtime a month or so ago and happens sporadically. Sometimes it would happen several times a day to the same person, other times it wouldn't happen to any of my caller for a whole week.

Those calls do not show up in the FPL call logs, so I think it's an FPL problem as opposed to a problem with my setup (I have the SIP credentials, so I run through an ATA). Any help is appreciated, and let me know if this is happening more generally. I need to know if FPL is still reliable enough that people can reach me.

[Bennyguy]

Hi,
I was having issues as well....when ever I try to call my number (or anyone else) I get a response saying the customer isn't available right now.

But as of now it's working again (04/25 at 7:55pm east standard time)

[bridonca]

This reeks of a router issue.

Here is the problem. The router's NAT lost track of the RTP port(s) on where to send the incoming call. Quick fix is to turn the modem, router, and ATA off, then turn on the modem. wait 30 sec, then turn on the router, wait another 30 seconds, then turn on the ATA. That might or might not temporarily fix the incoming call problem.

For a more permanent fix, you would need to forward RTP port(s) from the router, to the ATA. Your need to look at the ATA to see what RTP port(s) the ATA uses, and forward that from the router to the ATA. A good router with a decent firmware makes that easier.

[evilmonkey]

That actually may be the issue. I recently changed my SIP port to something non-standard on my router (so that people don't try to get into my PBX). I'll change it back and beef up security in other ways to see if this helps. Thanks for the tip, I didn't even consider that it could be a router issue. All my RTP (10-20,000) ports are properly forwarded.

[bridonca]

For most ATA devices, you only need 2 ports forwarded. A SIP port, and an RTP port. Some ATA devices might need more than one RTP port forwarded, so be it.

Rarely do you have problems with the SIP port, It usually takes care of itself. I tend not to even bother forwarding it, because I use different VOIP providers, and a lot of them insist on port 5060. In any case, it is not a bad idea to use another SIP port for Fongo like 6060, because not only is it great for security, it defeats a new feature on some of the newer craptacular routers, SIP ALG. SIP ALG is a useless feature that does not work well, but is still poorly implemented on some routers to add "value"

Now your problem with the incoming calls, is with the RTP port. As I said, you only need one or 2 of them forwarded to the ATA, but you have to make sure you know what the ATA device is actually accepting for an RTP port. You have to make sure nothing else is using that port, of course.

[evilmonkey]

My setup is a little more complicated: it's modem -> router -> IP PBX (asterisk) -> ATA (connected to the router, not the PBX) -> phone. My SIP port and RTP ports (all 10,000 of them) are forwarded to my PBX.

What's weird though is if the problem was the router, wouldn't FPL just send the call to voicemail as opposed to letting the user get a busy tone? And wouldn't I see it in FPL's logs?

[FONGO_steve]

If your registration to the SIP server drops without a de-register packet being sent then our server will still see you as being registered and will be trying to send calls to your user agent (causing a busy signal because you aren't technically registered anymore). Eventually the registration on our server refreshes, sees that you aren't there anymore, and triggers calls to voicemail.

If you're having this problem on a sporadic basis then something in your router or SIP client setup might be inadvertently dropping registration, blocking ports, etc.

[dibsmft]

evilmonkey
First, there is really no point in forwarding so many ports.....not quite sure what you are doing.
I guess an incoming invitation from FPL message is going to the PBX and when it gets there it goes nowhere. The busy tone may actually be fast busy that indicates anf error and the connection is never completed. Forward port 5061 UDP and ports 8000 - 8005 UDP to the ATA (what is it?) and configure those into the ATA and it should work. The alternative is to set FPL up on the PBX but you need an interface to connect the phone(...the ATA?)

[evilmonkey]

dibsmft,
My PBX connects to FPL and my ATA box connects to FPL via the router. Therefore, anything accessing the ATA is all internal to my LAN (PBX and ATA are on the same LAN), and there is no need to forward any ports to it.

Steve,
Thanks for the tip. I changed the port back to 5060 and I'll see if I have this problem again. I'm also troubleshooting a problem where another one of my trunks keep showing 'lagged'/'unreachable' every 20 minutes. Since I use that trunk to forward some of the FLP calls (so as not to abuse the FPL system), this may be what's causing my issues. I just expected to see the calls in FPL logs, so I thought it was an FPL issue when I didn't. Thanks!

[dibsmft]

The ATA is behind the same router so you will still need to forward ports to it. The PBX would also need to know what ports to listen/send to communicate with the ATA and vice versa for that matter.

[evilmonkey]

OK, thanks everyone. I made some changes, I'll wake this thread up if I keep getting complaints from callers.