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

shouldbe q931 shouldbeq931 at gmail.com
Fri Jun 17 21:33:59 MSD 2011

On Mon, Jun 13, 2011 at 7:55 AM, Mike Raistrick
<michael.raistrick at googlemail.com> wrote:
> 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
> number.
> 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
> 'national'.
> 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.
> Mike

>From my experience with BT, unless you have COLP, you will only send
the lead number of the trunk, you only need CLIR if you want to be
able to restrict

More information about the FreeSWITCH-users mailing list