Adding Asterisk to PBX

We have a Telrad Digital 128 PBX that's maxed out, and to add another 8-16 extensions would require upgrading the whole system at about $2000-$3000. Is it possible and practical to add the new extensions using Asterisk? If so, how would the Telrad PBX communicate with Asterisk? Where can I go for that kind of information? I'm sure I won't get much help integrating the PBX with the IP PBX from the vendor that sells and maintains the system for us. If this worked out, it would be a great way to get some experience with Asterisk and eventually replace the Telrad system entirely

Hi

How many extensions do you have on the Telrad ? and what are the lines that supply it? are they ISDN or Analog?

Ian

Thanks. We have 84 extensions and 15 lines delivered via T1. We may have to add as many as 16 extensions, forcing us to upgrade to a Telrad 400. I'd rather not spend more money on upgrading our PBX if I can take some incremental steps toward replacing it.

Hi

Ok the easiest is to insert an Asterisk server between the NT and the Telrad , It will mean buying a dual T1 card but it means you can migrate users easily from one to the other.

Code:

NT--------ASTRERISK-------TELRAD                |             |             IP EXTENSIONS   TDM EXTENSIONS

Ian

Thanks. So am I correct in assuming that one T1 port is the input from the carrier, and the other one will connect to the Telrad PBX? Where can I get more nuts and bolts info on making that connection? I'm guessing I'm going to need some PBX configuration from our Telrad vendor (who won't be thrilled with this whole direction).

Hi.

Ok You can get away without any intervention from your PBX supplier with this configuration.

I did write a small piece on this http://cyber-cottage.co.uk/site/index.p ... ;Itemid=60 . But as to nuts and bolts to doing it, What is you competency ? Have you set up and configured Asterisk servers ? and do you have access to T1 test equipment?

The basic theory is that the T1 from the CO will deliver calls to the * server , if it has a matching extension to a incoming DID it will pass the call over to that an ring the relevant IP phone, if not the call is passed tothe T1 to the telrad which receives it as a normal DID call and rings the extension.
Local users on the telrad to call an extension on the * server would dial as if they are dialling externally(this can be changed so they dial a 8 then the extension number.) this then goes down the T1 to the * and calls the extension. Users on * just dial extensions not caring which systems they are on as the system will know that if the extension isn't on the * it will be up the T1 and on the Telrad .

Ian

Thanks, That clarifies things a lot. When I started this thread, it was a toss-up between more Telrad, or expanding with VoIP. I was just informed that we'll need 30 more extensions, and half of those will be in another building for a couple months during remodeling. That seems to tip the scales clearly toward VoIP. And it needs to happen in 6 weeks. If I'm proficient with linux and networking, and tend to do well in self-taught situations, does that sound like a rational goal?

Hi,

I am looking into similar setup with a Telrad system. I have set up asterisk using trixbox and have a dual head openvox d210p isdn card but I am unsure how to connect it to the Telrad system, I have tried connecting to the Telrad’s N30 card and also to the PRI30 card but just get red lights on both sides. Has anyone had any luck with this and could you point me in the right direction.

Thanks.

Turned out to be a faulty cable. I can now ring the asterisk box from the telrad PBX.I am still unsure how to get the incoming calls that dont have an extension on asterisk to passover to the second span and onto the terad, if anyone can offer any suggestions.

Thanks

Hi

Ok this is very simple, lets say for example ZAP/G2/ is the route to the teltad and the incoming DDI range is 1000 -1999

then at its simplest

exten _1XXX,1,Dial(SIP/${EXTEN},tT,30)
exten _1XXX,n,Dial(ZAP/G2/${EXTEN})

Obviously this can be expanded upon
for example

exten _1XXX,1,Dial(Local/${EXTEN}@default)
exten _1XXX,n,Dial(ZAP/G2/${EXTEN})

Ian

Thanks' Ian,

I have another problem, If I set in the Zapata.conf the signalling to pri_net then I can transfer calls to the Telrad PBX but then get a busy signal when I dial in. If I set the signalling to pri_cpe I can dial in but cannot connect to the Telrad. Is there anyway to set Span 1 (my incoming line) to pri_cpe and Span 2 (connection to Telrad) pri_net?

Thanks again.

Dan

Hi post your zapata.conf and I can set it if you want but basicly it need to end like this

group=1
signalling=pri_cpe
channel => 1-15,17-31
group=2
signalling=pri_net
channel => 32-46,48-62

Ian

Thanks again Ian,

Zapata.conf

[channels]

language=en

context=from-zaptel

switchtype=euroisdn

pridialplan=national

signalling = pri_cpe

;signalling = pri_net

usecallerid=yes

hidecallerid=no

callwaiting=yes

usecallingpres=yes

callwaitingcallerid=yes

threewaycalling=yes

transfer=yes

canpark=yes

cancallforward=yes

callreturn=yes

echocancel=yes

echocancelwhenbridged=yes

rxgain=0.0

txgain=0.0



group=1

channel =>1-15, 17-31

immediate=no

signalling = pri_cpe



group = 2

channel => 32-46, 48-62

signalling = pri_net

Hi It looks wrong at the end

see my example

Ian

Hi Ian,

Thanks again. The system I am experimenting on is live so my time windows for testing are very limited. I now cannot get my Telrad phone to call out numbers, in my 'extensions_custom.conf' I have added :

exten => s,n,Dial(ZAP/G1/{EXTEN})

but looking at the output it does not seem to pass the number dialled and then hangs up.

-- Executing [s@from-pstn:3] Dial("Zap/32-1", "ZAP/G1/") in new stack
-- Requested transfer capability: 0x00 - SPEECH
-- Called G1/
-- Zap/31-1 is proceeding passing it to Zap/32-1
-- Channel 0/31, span 1 got hangup request, cause 28
-- Hungup 'Zap/31-1'

Thanks again

Dan