[asterisk-biz] Questions about isdn/pri/e1 services

[Chris Bagnall]

Hi there,

> I want to find out about services required to have incoming pstn connections to
> asterisk. So I understand isdn/pri/e1 circuit and channels is required to enable
> this.

ISDN is one of your options for getting incoming calls into an Asterisk system. You'll need an appropriate ISDN card (Digium sell various different models - which one you'll need will depend on how many channels you want to have, and the hardware in your planned Asterisk server). There are other third-party suppliers of ISDN cards - Junghanns and OpenVox spring to mind. I've used the Digium and OpenVox cards successfully, but don't have any experience with any others.

> What about the phone numbers set to the pri, how many different numbers can
> be set and how are numbers assigned to the circuit.

Theoretically, on a full ISDN30 you can have any number of DDIs, but you only have 30 channels. One of our clients as over 1000 numbers on a single ISDN30, but this is somewhat rare in these days of number shortages. The regulator (Ofcom) does like to ensure numbers allocated are actually being used, so the days of allocating huge ranges then only using a fraction of them are probably over.

> Do you have to go through
> the same company providing the pri to get the numbers or can these be
> purchased and set from seperate providers.

Usually you'd use the same company to provide the ISDN as the numbers. I'm not sure if it's possible to use different companies - my guess would be not, but I'm open to correction on that one.

> Which companies in the UK provide
> isdn/pri/e1 lines services.

<shameless plug>We do! Contact me offlist for more details and pricing.</shameless plug>

Beyond that, the usual suspects will be quite happy to sell you an ISDN30 I'm sure: BT, Virgin Media, Kingston Communications are three of the bigger players that immediately come to mind. There are many other providers that resell BT's wholesale services under the WLR system (wholesale line rental), so pretty much any Telco in the UK should be able to sort you out an ISDN.

> Are pri lines avaible at data centres for servers located/hosted.

We can certainly deliver PRIs into datacentres - again, contact me offlist for further details.

> Finally what are the costs involved to get set up and the typical pricing
> structures.

If you aren't wanting to sign up to a $many_years contract, you'd expect to pay a fairly substantial installation charge, followed by a monthly charge per channel and a small monthly charge per DDI. There are companies out there which will reduce (or even eliminate) the installation charge in exchange for a ridiculously long contract (3 or 5 years). I'd advise steering clear of those, even if they do look attractive initially - tying yourself to a product for 3 or 5 years in a market moving as fast as this one would be unwise, in my opinion.

I mentioned at the start that ISDN was one of the options for delivering calls into your Asterisk system. You can of course deliver calls to your system via SIP or IAX as well. Indeed, most of our installations over the last couple of years have avoided ISDN entirely (or just kept a small ISDN2 for backup purposes), and instead make and receive all calls via the IP network, either over a leased line or even an ordinary ADSL connection (provided it's not being used for data as well - mixing voice and data will earn you an eternity of call quality problems).

Delivery via IP has the advantage of being location independent - if you move, you can take the numbers with you, whereas on an ISDN they're tied to the local exchange from which they came. It's also decidedly cheaper and doesn't involve any minimum contract terms (if you do it through us :-) ).

Hope that helps.

Regards,

Chris
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