Setting up a new carrier (e.g. telasip)

Usually, setting up a new carrier definition is very straightforward, however the whole field of VOIP telephony is exploding at time of writing and many of the newer carriers know little or nothing of Asterisk (or very much else for that matter) and as a result you will occasionally come across unconventional or just plain silly set-up requirements and instructions. Below is a quick howto on setting up a carrier entry and trunk for telasip, a popular, new(ish) US carrier.

Overview

Registration

In order to understand carriers you need to understand a little about registration and whether it is necessary or not. Registration is not necessary with a carrier; IF, the carrier knows where you are and how to reach you. Carriers such as Telappliant and Gradwell in the UK do not require you to register, however they DO require you to tell them (in an interactive browser panel) WHERE to deliver inbound calls. Registration, tells the carrier where you are and (optionally) how to deliver the inbound call. The general format for a registration string is

user-id:password@carrierURI/deliverytag

User-id, password & carrierURI are self-explanatory. deliverytag instructs the carrier which number or sipaddress to deliver the call to. In theory, a registration string of

selintra:selpass@sip.mycarrier.com/01924918076

registers with the carrier and requests that inbound calls be delivered with an inbound number of 01924918076.

However, many carriers ignore the delivery tag and deliver either against the dialled number or (rather stupidly) against the User-id (often called the account number).

PEERs, & USERs.

Often, your carrier will give lengthy instructions for peer and user entries. In general you should NEVER need a user entry for a SIP carrier (despite what the carrier may say). Contrarywise, you will ALWAYS need a user entry for an inbound IAX call. Asterisk will accept any sip call directed at it as long as it can find the delivered number (or sip address) in the extensions context referenced in sip.conf.

In the peer entry you will usually only need the following...

type=peer
host= hostURI
username= account name/number
secret= password
disallow=all
allow= codec-1
.
.
.
allow= codec-n

Additionally, if the carrier requires you to register, then you will need...

insecure=very

Many carriers insist on the fromuser tuple and it does no harm to include it so...

fromuser= account name/number

SAIL also adds a timeout and denies re-invites so it adds

canreinvite=no
qualify=3000

And that's it.

telasip set-up

Fisrt we create a new carrier definition for telasip

<img src="/docs/images/V2.0/carrier_setup1.jpg"

The only modification is to add the insecure=very tuple

<img src="/docs/images/V2.0/carrier_setup2.jpg"

Now we can add the trunk

<img src="/docs/images/V2.0/carrier_setup3.jpg"

Standard set up for telasip - inbound number (DID) in the did field and a unique sip context name followed by the carrier uri, user-id and password.

<img src="/docs/images/V2.0/carrier_setup4.jpg"

And here's the final trunk ready to use. You will have to create a route or (as we have done here), add a "trunk pre-select" string (we've chosen 44).

<img src="/docs/images/V2.0/carrier_setup5.jpg"