Inbound Calls are Failing

A very common complaint received by our support staff is that Inbound calls are not working. The cause of this situation can be broken into three categories:

1. Trunk is not registered

2. Trunk is registered to wrong IP Address and/or port

3. Trunk is registered correctly but inbound routes are misconfigured

This guide should help you troubleshoot your inbound calling issue and give you some common solutions applicable to most situations.

Step 1: Log in to your portal and look for your trunk registration. This is found by going to the “SIP Trunking” tab. Within that tab, you should see a screen like the one below. There will be a section for each trunk that you may have.

Step 2: Note the “REGISTRATION STATUS.” Does it say “REGISTERED” in green, or “NOT REGISTERED” in red. If your trunk is in the “NOT REGISTERED” status, SIP.US has no idea where to send your calls to. And you will not receive calls.

Step 3: Note the line below “REGISTRATION STATUS.” If you have successfully registered your PBX/Phone with our service you should see a string like this (the string is edited out of the image above for privacy/security):

(GW1) sip:s@<YOUR IP ADDRESS>:<YOUR PORT>/<YOUR SYSTEM TYPE>

Inspect the IP address and port very carefully. If the IP address displayed falls in the following ranges, we will be unable to deliver your calls:

10.0.0.0 – 10.255.255.255

172.16.0.0 – 172.31.255.255

192.168.0.0 – 192.168.255.255

That is because these are private IP addresses which are used within your Local Area Network (LAN). These addresses are not route-able on the internet. Your ISP gives you/your router a public IP address which is not in those ranges. That public IP address is the one that needs to be in the string. To find your public IP address simply Google “What is my IP.” Your public IP should be returned as the top result.

Now inspect the port in your string. It is the number after the colon and before the forward-slash. Is that port the one you have set your system to register to? (Most PBX systems use port 5060). If the port is some funky number like 49784, chances are your firewall/router is doing PAT. This doesn't mean your calls won't work, but they may not work intermittently (the cause of the intermittent issue is beyond the scope of this article). The best solution is to use 1:1 port translation so that your port does not change through translation.

If you cannot seem to get your public IP and port combination to show up in the string, you may want to use a STUN server. Within most phones/PBX systems there is a field to input a STUN server. You may use ours by putting in “stun.sip.us” in the field for “STUN Server” on your system.

Step 4: If you are registered correctly, but calls are still failing to reach you, it's time to consider your inbound routes. Each PBX uses a different configuration for inbound routes. Please refer to the SIP.US guide for your specific system. It's important to note that we will deliver the call with a “1” in front. So if your number is 333-444-5555 we will deliver it as “13334445555.” Many PBX systems have a “wildcard” inbound route that allows any number delivered to the system to ring and reach a destination. We highly recommend using wildcard routes for troubleshooting and then locking the system down later.

Finally, be sure that you have actually routed calls somewhere. You need to specify a destination for calls. You could direct your calls to an extension, voicemail, an automated attendant. We recommend getting an extension set up and directing calls there to start out. However, if you are having trouble you may want to switch to voicemail or an automated attendant to eliminate the extension as the issue.

If you have gone through this document and still cannot receive calls, please open a support ticket with SIP.US and we will assist you further.