[Freeswitch-users] UK ISDN outgoing CLI (was Re: FreeTDM - Sangoma B700 - ISDN connection questions - UK)

Mike Raistrick michael.raistrick at googlemail.com
Mon Jun 13 10:55:10 MSD 2011

I've no direct experience with BT BRA ISDN (plenty with other providers) -
but I don't think that CLIP / COLP will be the issue.

CLIP is an inbound service - and determines whether your equipment is
presented with the number of the person calling you (and if they allow it).

Although COLP is an outbound service, it is used to display the number of
the line that you are connected through to (which might not be the same as
the number you dialled - e.g. 0800 numbers).

Whilst we're on supplementary services, CLIR is also an outbound service and
allows you to specify whether the CLI that you send (or the one that BT
uses) can be shown to the person you call.

Some terminogy: ISDN Basic Rate differentiates Direct Dial In (DDI's) and
Multiple Subscriber Numbers (MSNs) for incoming services.

DDIs are designed for PBXs and are associated with a range of numbers in a
block. The service provider sends you a called party number that can range
either from the last 'X' digits through to the whole number - this is
normally specified when the service is ordered and then all calls are
delivered the same way.

With DDIs - when you send an outgoing call you should be able to send the
extension or the whole number - in either case you should mark the Type Of
Number field accordingly (and if in national format - not include the '0'
for the number itself). In case that you send the extension digits - the
service provider adds this to the DDI 'stem' to get the full number. With
the full number (either derived from the extension, or as you sent it) - the
provider should then check that the number is in the allocated DDI range -
if it is it will allow it through, if not it will usually send the root DDI

MSNs are unique to BRA - they are completely separate telephone numbers and
were originally designed to allow multiple BRA phones to be off the same
ISDN bus and have their own phone numbers. This means that the full number
will always be sent to you, and be expected from you for called and calling
numbers (still with the right Type Of Number set..).

Summary - with either DDI or MSNs - you should be OK to send the whole
number to BT as the calling party - minus the '0' and with TON set to

Finally - if you do have the CLIR supplementary service, make sure that you
set the presentation indicator to 'allowed' - default should normally be to
assume allowed unless set differently - but to be on the safe side.


On Fri, Jun 10, 2011 at 11:22 AM, John <freeswitch at earthspike.net> wrote:

> Shouldbe,
> You won't be burned at the stake for heresy and are probably right that
> this is the problem, as we have had delays in getting CLIP implemented.
>  From your comment I assume that COLP is not automatically enabled (even
> though I am paying for additional SNDDIs) but has to be ordered
> specifically.  Our service provider is on to it, and I am waiting till
> CLIP/COLP is applied before doing any more testing.  I'll post here with
> the results.
> John
> On 10/06/11 10:08, shouldbe q931 wrote:
> > On Thu, Jun 9, 2011 at 7:10 PM, John<freeswitch at earthspike.net>  wrote:
> >> [I've forked this thread as it really should have been 3 separate
> >> threads to start with.]
> >>
> >> Thanks,
> >>
> >> I have tried every combination I can think of, except 10 digits which I
> >> will give a go.  That makes sense as in the general case it would permit
> >> non-geographical numbers to be presented.
> >>
> >> The lines are provided as 2 x ISDN2e with a lead number covering all 4
> >> channels.  The NTE8s are labelled 1-2 and 3-4, so not separate
> >> individual lines, I thnk.
> >>
> >> We currently have a Single Number DDI in addition, and hope to increase
> >> that to 2 very soon; the 3 numbers between them will serve 3 separate
> >> business units, so we want to be able to present the correct outbound
> >> CLI from each business unit.  We also have a remote call forward from
> >> another number to the lead number, but presenting that really would be
> >> CLI spoofing, so I am not expecting that to be permissible. But I would
> >> expect those that are directly allocated to the 2 lines/4 channels to be
> >> allowed to be presented.
> >>
> >> John
> >>
> >> On 09/06/11 08:27, shouldbe q931 wrote:
> >>> On Mon, Jun 6, 2011 at 10:36 PM, John<freeswitch at earthspike.net>
>  wrote:
> >>>> Hello,
> >>>>
> >>> <snipped for brevity>
> >>>> 2. We have 2 Single Number DDI numbers configured over the 4 channels.
> >>>> I want to set up outgoing calls so that they can appear to come from
> >>>> either of the two numbers, but at present the outgoing CLI appears to
> be
> >>>> overridden by the telco (BT) to only use one of the numbers.  Has
> anyone
> >>>> got this working in UK, and what is the format for the
> >>>> outbound_caller_id_number: last 6 digits or full 11 digits?  I note
> that
> >>>> the inbound called number is only the last 6 digits.
> >>>>
> >>> <snipped for brevity>
> >>>> Thanks for all the great support I have already got just from editing
> my
> >>>> Wiki User page; this is a friendly group!
> >>>>
> >>>> John
> >>>>
> >>> I can only comment on the BT part.
> >>>
> >>> If they are two individual lines, you're out of luck with BT, as they
> >>> do not allow CLI spoofing, which this would be.
> >>>
> >>> I would suggest sending BT the same number of digits that they send
> >>> you, if that doesn't work try 10 digits. If  you are not sending the
> >>> "correct" number of digits for a valid DDI on the trunk, then they
> >>> will send the lead number for the trunk.
> >>>
> >>> Cheers
> >>>
> >>> _______________________________________________
> > I know that this might sound like heresy :-)  but have you checked
> > spoken to BT and asked them if CLIP and CLOP on the lines ?
> >
> > I think CLOP is outbound and CLIP is inbound, but I might have it the
> > wrong way round...
> >
> > _______________________________________________
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