Playing with Asterisk and VOIP

I haven’t written much recently – the day job keeps getting in the way 🙁

Anyway – some of my spare time has been used getting Asterisk working just the way we want. The more I play with it, the more I really like it.

We now have multiple voice mail accounts set-up for our various business interests, linked to an Automated Attendant or IVR (which is currently using my voice, but we are hoping to get one of our wives to record the greetings as girls are better than boys!). Once the caller has pressed the appropriate digit on their phone, Asterisk simultaneously calls multiple extensions (some on another Asterisk server connected across the ‘net), and if no-one answers within a pre-defined time, then the call is routed to the relevant voice mail account. The audio message left by the caller is then attached and emailed to one or more recipients depending on how we configure Asterisk and Exim. When the call is initially presented to our SIP phones, not only do we see the caller ID (which we could use to trigger application events in a CRM like vtiger for example), but we also see which business (or choice) the caller selected, thus we are able to appropriately answer the call.

This is a pretty advanced feature set for any PBX. But when you realise it’s running on a box that cost under £200, which also provides file server, content filtering/firewall, and local web based, application services too, and the software costs have been zero, it’s really quite amazing. Obviously for more “serious” telephony you’d want to run Asterisk on hardware that is designed to be ultra-reliable. But still the software is free. However for a home or home-office set-up I would suggest that this is an excellent platform.

The other thing I have just set-up is a free (for me) local rate DID (Direct Inward Dialling) number that connects, via the net, to my asterisk server using the IAX2 protocol. The provider of the service is the not-for-profit organisation This is quite an amazing service:

VoIP User is a non-profit community, formed with the intention of creating a base for early adopters, consumers and professionals alike to exchange ideas, discuss new developments and generally experiment with VoIP technology.We have a natural bias toward open standards. In the VoIP space, this is primarily SIP and IAX (Asterisk).

When we started building the foundations of what became VoIP User at the end of 2002 there was nothing available to the developer and early adopter that enabled experimentation with PSTN gateways. Of course with the majority of telephone users on the PSTN, only being able to call another VoIP User in a test environment was too restrictive – some form of free access gateway was required.

In order to fill this need we setup a service system provisioning a PSTN/VoIP gateway for public access at no charge. In order to make this possible we created a unique financial model whereby calls outbound from the gateway are financed by calls inbound to the gateway. Every member signing up for access obtains an inbound PSTN number, on which revenue is generated and VoIP User receives a share. It’s that share of revenue that funds the outbound calls.

All inbound funds are credited to a central “pot” which is made available to those members who are making reasonable use of the facility. Excessive use is dealt with by member and number restrictions. We aim to run this in as fair and reasonable a manner as we possibly can but the over-riding principle is it is offered for experimentational use. We are not a VoIP provider. If you require long term telephony services, you will need to look elsewhere. If you’re looking to test a new piece of SIP or Asterisk equipment, you’re in the right place.

As they state, this service is for experimentation and testing but it works, is very easy to setup and has enabled me to test many of the features of Asterisk. If you are going to start experimenting, pay them a visit. And remember incoming calls are charged at the UK local call rate, and as long as you don’t abuse the service, outbound PSTN calls are free.

Back to the grindstone then…

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