UK Voip with DDI

Hi all,

I’m looking to replicate an existing system, a company has 100 incoming lines (e.g 01234 567000 to 01234 567099) and each of these DDIs determines how the call handler answers the phone.

During my trials I am using VoipFone and I’m currently finding that I will need to buy 100 numbers ( at £2 a month ex VAT) , 100 extensions ( at £1 a month ex VAT ) and I will need to set up 100 trunks and 100 incoming routes with 100 ring groups (It’s at the ring group stage that I inject the “whisper number” using CID Name prefix option).

So we’re talking £300 a month ex VAT without even considering the call costs.

Is there an easier/cheaper way of doing this? I would like to route incoming calls based on the DDI (which voipfone doesn’t supply apparently).

Am I able to do this with alternative UK SIP Voip providers?


You presumably currently have a PRI circuit, it might be cheaper to continue using it with a sip gateway or a “dahdi” hardware card for your inbound calls which are probably included in the PRI cost. Then just buy pay per minute outbound voip service.

If you use the context [from-did-direct] for that trunk then the PRI’s DDI’s can be matched one to one against your “endpoints” (extensions, RingGroups Queues etc.)

If you go the VOIP route it is easy to map many routes IF they are unique in a similar fashion by building a custom context

exten => _X.,1,Goto(from-pstn,${EXTEN:-4},1) # perhaps 3 but that can cause collisions with other services.

This will save you from the one hundred inbound routes otherwise needed.

We use a company called Gamma ( for our SIP trunk.
We have 16 channels, with 1000 DDI’s. Roughly the install charges were £90 for the SIP and £140 for 1000 DDI’s. Monthly rental cost is about £130, which includes 80000 minutes to UK fixed line calls. A lot cheaper than our old analogue lines :smile:

Hi Dicko, Byteguy, thanks for the responses : )

Dicko, I didn’t know what a PRI circuit was until you mentioned it, but it seems like an analogue thing, where as their current phone system is SIP based (Avaya IP Office 8). Sorry, maybe when I said incoming lines I used to wrong terminology, they are in fact 100 DDIs?

Byteguy, can you confirm the incoming calls are reporting the correct DDI within freepbx? I’ll give them a go if it is! : )

Thanks again

Yes the incoming calls report the correct DDI and we route on that to the correct extension or to a Queue, Ring Group etc. We also have quite a few other phone numbers that have been migrated from analogue that now come in on the same SIP and route these to the correct destination eg fax.
Outgoing calls also send the correct CLID as required.

Nice one cheers :slight_smile: I will give them a look!