Customizing CAS…

Ever been troubleshooting an issue to find the problem was you left out a single line of code – code you never knew needed to be there?  I’m betting anyone who’s been in IT for any length of time has been there, done that- and nearly pulled his/her hair out in the process. (Why do you think there are so many balding guys in IT?)

Case in point – team lead and I are bringing up E1 circuit in Mexico, resting comfortably in the knowledge that we’ve done this before. The fact that we have no idea how many digits the carrier is going to be sending doesn’t even phase us, we’ve got mad translating skills – bring it on.

That is until it’s clear that whatever digits the carrier is sending, the router is less than thrilled with. No modification of the incoming translation pattern appeases the angry stream of incoming digits- whatever they may be.

Fast forward about two hours and quite a number of debugs later and say hi to the Australian TAC engineer, who is now on the line with us, two IT guys at the site, and a Mexican telco engineer.  Only problem – no one but the telco engineer speaks Spanish – and we’re pretty sure everything that’s wrong is his fault.  He is the telco guy after all.

In the bizarre world of coincidences, the Australian TAC guy (with the really great accent, btw) pipes up with  “hey, the guy in the cube next to me happens to speak Spanish” – and with that our international summit gains traction.  Shortly after, we are staring in awe at the magic line of code that makes everything in this particularly odd universe super happy.

What was missing? This line: groupa-callerid-end. Yep, all this madness and mayhem over that one single line.  It goes here:

controller E1 0/0/0
framing NO-CRC4
ds0-group 1 timeslots 1-15,17-30 type r2-digital r2-compelled ani
cas-custom 1
country telmex
category 2
answer-signal group-b 1
groupa-callerid-end  

Now will you always need this command when bringing up E1s?  Nope.  Will this fix all your issues with telcos in Mexico?  Not likely.  But it’s definitely something to make note of.  Especially when you find yourself doing a bit of guesswork due to a certain lack of information and relatively huge language gap with the carrier.

As an added bonus and completely unrelated to the issue above – here are some dial-peers for common patterns in Mexico that might prove useful if you are planning on bringing up a site there.  Think of it as your treat for making it to the end of this post.

dial-peer voice 2 pots
description Local Dialing
destination-pattern 9[1-9]…….
port 0/1/0:1
forward-digits 8
!
dial-peer voice 91 pots
description Long distance
destination-pattern 901……….
port 0/1/0:1
forward-digits 12
!
dial-peer voice 9011 pots
description International Dialing
destination-pattern 900T
port 0/1/0:1
prefix 00
!
dial-peer voice 44 pots
description Local Cell Phone
destination-pattern 9044……….$
port 0/1/0:1
forward-digits 13
!
dial-peer voice 45 pots
description Long Distance Cell Phone
destination-pattern 9045……….$
port 0/1/0:1
forward-digits 13
!
dial-peer voice 60 pots
description Emergency Services
destination-pattern 060
port 0/1/0:1
forward-digits all
!
dial-peer voice 9060 pots
description Emergency Services
destination-pattern 906.$
port 0/1/0:1
forward-digits 3

dial-peer voice 9070 pots
description Information & Electric Repairs
destination-pattern 907[01]
port 0/1/0:1
forward-digits 3
!
dial-peer voice 9050 pots
description Telephone Repair
destination-pattern 9050
port 0/1/0:1
forward-digits 3
!
dial-peer voice 9040 pots
description Information
destination-pattern 9040$
port 0/1/0:1
forward-digits 3