Tag Archives: ddi

Inbound Number (DDI/DID) with FreePBX 2.10

Setting up an Inbound Number with FreePBX can be tricky. There are a few different things to consider and in the past I’ve written some posts for setting up specific call providers. This post will try to describe what the different options mean, and will hopefully help you set up a DDI number with any provider.

The first thing you need to know is that all SysAdminMan templates have “Allow Anonymous Inbound SIP Calls” set to No. This means that an unknown SIP server can not pass a call to your system to be processed. This is to help prevent hackers route calls through your system. It’s strongly recommended that you leave Anonymous SIP calls set to No, unless you really know what the implications are when setting it to Yes.

So, if we don’t let any SIP servers pass calls to us then we need a way to tell FreePBX to allow calls from our DDI provider. We do this by setting up a SIP trunk.

Setting up a SIP trunk

We are going to put all of the settings under “Outgoing settings”, and leave “Incoming settings” blank. This is a little confusing to say the least! but we are not creating a user on our system for the call provider to connect to, we are just allowing their IP. So we add a new SIP trunk and see these details –

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FreePBX: Inbound number not working help

Setting up an Inbound (DID/DDI) number in FreePBX can be tricky. We have to do 2 things to get it to work. First we need to tell FreePBX/Asterisk that the incoming call is allowed, the second is to say what to do with that incoming call.

Lets look at allowing the call first. One of the easiest ways to do this is allow Anonymous SIP Calls in FreePBX. I recommend you do not do this though as you don’t really want Asterisk/FreePBX trying to process any call fired at it.

So if we’re not going to allow anonymous SIP calls we need to tell Asterisk what IPs to allow calls from, and we do this by setting up a trunk. When a call comes to our server we will receive a SIP INVITE from the remote server, asking us to accept the call, so let’s have a look at the SIP INVITE messages coming in …

First we’ll install ‘tcpdump’ if it’s not already on the system. In CentOS we do –

yum -y install tcpdump

Next we run the following command to list all the INVITE messages coming in. You will need to change the network adapter name if you’re not on a VPS, probably from venet0 to eth0 –

tcpdump -i venet0 -n -s 0 port 5060 -vvv | grep -B1 "INVITE sip"

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A2Billing – assigning an inbound number to a customer

Assigning an inbound number to a customer is fairly easy to achieve in A2Billing. Once assigned the customer can use the web interface to change the destination of that inbound number.

First you are going to need an inbound number from a DID/DDI provider. I’m going to use DIDX.net in this example.

We need to set the SIP URI destination for the inbound number with our DDI provider. In the DIDX control panel I’ve set the destination of a London DDI¬† (country code 44 / city code 20) to my demo server –

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