03-25-2004 02:47 PM - edited 03-13-2019 04:26 AM
-Office A has (2) Call Managers
-Office B has Catalyst 4224 with IP phones
-4 digit dialing setup between offices
If the T1 connection between office A and B is dropped and a user in Office B places a 4 digit call is it possible to re-route the 4 digit call to the PSTN and place the long distance call automatically? We do have an ISDN backup and when that kicks in would it still be possible to re-route the calls until the T1 is re-established?
Thanks!
03-25-2004 09:40 PM
Chris,
If the T1 between A and B goes down you can route the four digit calls to the PSTN. You need to have SRST set up on the 4224, appropriate dial peers, and you can use num-exp to make the four digits into what you need for the LD call. Like this:
num-exp 2... 918648552...
The expanded number will then match on the dial peers.
If you have ISDN backup working, IP calls and the CM connection will continue across it, though the limited bandwidth and QoS may be an issue.
Mike
03-25-2004 10:11 PM
Thats correct, and an alternate to num-exp would be to use translation rules.
translation-rule 1
rule 1 2 918648552
call-manager-fallback
translate called 1
03-26-2004 06:04 AM
Thanks for the information! We do have SRST setup on the 4224 and it is working, but I was hoping that there is a way to detect and/or route calls to the PSTN if the ISDN kicks in (to avoid calls going over a slow connection). The only real use for the ISDN is for the UNity server to be in contact with the CM.
Any other thoughts as to a better backup method when the T1 goes down? Does anyone use a decentralized model with your call managers?
03-26-2004 11:26 AM
Hi -
To block VoIP traffic from going over your ISDN line use ACLs under your BRI interface. You do not want VoIP traffic on your ISDN line. It is way too slow and should be reserved for non-voice data only when your primary T1 is down.
The below example will force your phones and gateway to go into fallback mode.
Ex:
interface BRI0/0
ip access-group 101 out
ip access-group 102 in
access-list 101 remark The following line blocks SCCP
access-list 101 deny tcp any any range 2000 2002
access-list 101 remark The following lines block MGCP
access-list 101 deny udp any any eq 2427
access-list 101 deny tcp any any eq 2428
access-list 101 permit ip any any
access-list 102 remark The following line blocks SCCP
access-list 102 deny tcp any range 2000 2002 any
access-list 102 remark The following lines block MGCP
access-list 102 deny tcp any eq 2428 any
access-list 102 deny udp any eq 2427 any
access-list 102 permit ip any any
-Jaret
03-26-2004 12:17 PM
Thanks Jaret! I will give it a try.
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