(UK) BT ASDH NTE 4U / 7A router ... and Asterisk

Hello,

I visited a UK based taxi cab company today where I found a 7+ year old setup comprising fibre lines connecting to a BT ASDH NTE 4U / 7A router with a CAT5 cable connecting from the router to a Norstar Meridian phone system.

I have never come across this setup before and am not familiar with SDH technology. The company thinks they have 15 phone lines. I could not clarify this.

Assuming that the ASDH router presents the phone lines to the Norstar switch as E1 / T1, I went about configuring a Digium TE220 as follows;

[code]chan_dahdi.conf

[channels]
language=uk
context=internal

echocancel=yes
echocancelwhenbridged=no
echotraining=yes

nationalprefix=0
internationalprefix=00
pridialplan=unknown
prilocaldialplan=unknown
callerid=asreceived
usecallerid=yes

switchtype=euroisdn
context=from-pstn
signalling=pri_cpe
group=1
channel => 1-15

dahdi/system.conf

loadzone=uk
defaultzone=uk

span=1,1,0,ccs,hdb3,crc4
bchan=1-15
dchan=16[/code]

I am using the latest versions of Asterisk;

[ul]Asterisk 1.4.26.1
DAHDI Linux 2.2.0.2
DAHDI Tools 2.2.0
Libpri 1.4.10.1
Addons 1.4.9[/ul]

When I connected the card to the ASDH router, both ends appeared to sync (i.e. the lights at each end went green) but the DAHDI channels stayed in RED ALARM and incoming calls could not be received (usual dead tone). There was no information in the Asterisk log at all. At this point, I didn’t want to test/debug this any further without knowing what I was dealing with. I have tried researching the configuration but without any success.

I am therefore posting in the hope that someone will be familiar with this type of equipment or will be able to clarify that the ASDH router is indeed presenting E1 / T1 to the switch and if so, advise on what settings I need to configure Asterisk / Dahdi with to get this working?

Many thanks

Colin

Hi

We have E1 here in the UK :wink:

its not a router its a Network Terminating Unit .

if the presentation is 120ohm or as you describe cat5 then its ISDN30e or PRI or E1. and as its from BT its type 110 not type 85

you also need to set all channels in the system.conf fro BT isdn circuits

span=1,1,0,ccs,hdb3,crc4
bchan=1-15
dchan=16
bchan=17-31

other than that looks OK , try it without the prefix settings ,
I assume the problem is that it doesnt work on site, Did it work when you set up the server before taking it to site ? also does the circuit work when you plug a tester in? or the Norstar ?

Ian
www.cyber-cottage.co.uk

Hi Ian,

Thank you very much for your speedy reply.

The circuit works fine when connected to the Norstar and the Asterisk card works fine when connected to what I would call a modern BT ISDN 30 circuit (albeit in a different server with a different version of Asterisk / DAHDI).

The problem I had was that I was unsure as to whether or not the circuit was E1 since I had never come across this type of NTU before and could not find any information about it.

Thanks for clearing that up, I should be able to get this working now.

Regards,

Colin

No worries, It may well be that you haven’t spec’d all the channels.

BT links very often wont come up unless all channels are configured, this is common to all PBXs.

I have page on alarms cyber-cottage.co.uk/site/index.p … &Itemid=63.

and as the physical is ok (green lights) but looks like l2 and l3 are down

It may be worth checking with BT that its type 110 and not type 85 , Dont expect them to understand but they may understand full etsi compliant

Ian

btw are you the same colinc who downloaded the packt book today :wink:

Hi Ian,

Thanks again for the help.

Yes, that was me. I had heared about the book (http://www.packtpub.com/asterisk-1-4-the-professionals-guide/) a few months back from Colman and David. It looks excellent and I’m looking forward to receiving the hard copy.

Colin

Hi,

A further update …

It seems that the NTU is providing DASS signalling and not EuroISDN and so is not compatible with Asterisk.

We are looking at getting a protocol convertor (DAS -> EuroISDN). If anybody has and recommendations they would be much appreciated.

Many thanks,

Colin

Hi Colin

Ive sent you a PM, But basicly you have to get BT to change the protocol, A converter is going to cost more than the asterisk server and card alone.

Ian

Hi,

Thanks again Ian for your help the other day.

It may be of interest that I found a device that can convert DASS to EuroISDN (and indeed EuroISDN to DASS) for a fairly reasonable price (www.nxgear.com).

There is also a version of this device that offers an additional SIP Gateway.

Thanks,

Colin