Channel selection on Cisco VoiceGateway

Answered Question
Apr 29th, 2010
User Badges:

We have a mgcp Cisco 3845 VoiceGateway with several Controllers having multiple PRI with our Provider.


What I need to know is, how can we setup a group of channels on a Controller to be "only" inbound or outbound?


We need to reserve channel 1-10 for only inbound calls and 11-31 for only outbound calls (15 is the D channel having an E1) or at least we need that our CUCM doesn't send outbound calls to the first 10 channels that are dedicated only to receive calls.



Thanks you

Correct Answer by allan.thomas about 6 years 11 months ago

Hi Lorenzo,


My apologies, I made the assumption that you are using MGCP, can you confirm whether you are using MGCP or H.323? This is simply because with H.323 it is more flexible than that of the options you have with MGCP as I have already menionted.


Regards

Allan.

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (2 ratings)
Loading.
allan.thomas Fri, 04/30/2010 - 00:16
User Badges:
  • Blue, 1500 points or more

Hi,


Unfortunately you cannot dictate which channels are used for inbound calls, however you can influence outgoing.  You basically have two options for controlling which MGCP endpoint is used for outgoing or channel-selection.


This can be acheived by either configuring your route-list to order your MGCP endpoints in the order you require to ensure that the first gateway is not the initial gateway where inbound calls originate.  For example, lets say that you have two endpoints 01 and 02, both are configured for inbound and outbound, however depending on your carrier inbound calls are possibly presented on timeslots 1-31 on endpoint 01 before 02.  If this is the case then you can order your endpoints within your route-list so that 02 is ordered before 01.  In this scenario all your outgoing will be routed via timeslots 1-31 on 02 before subsequent calls will go out on 01.


This largely depends on your carrier, as with some carriers dual-parenting dictates that channels are used in a round-robin fashion, timeslot 1 on 01 and then the next inbound call comes in on timeslot 1 on 02, timeslot 2 on 01, timeslot 02 on 02 and so on... Your carrier should be able to tell you how your inbound calls are routed, or you can either ascertain this from debugging the gateways and see the incoming call setup.


By default channel-selection on MGCP endpoints is BOTTOM-UP for your outgoing calls, which means that calls will go out initially on timeslots 31,30, 29 etc.., and most carrier inbound calls come in TOP-DOWN 1,2,3,4 etc. Unless this has be reconfigured on your endpoints, your calls should be going out on from 31 down.


Regards

Allan.


Hope this helps.

Biondilo Fri, 04/30/2010 - 00:28
User Badges:

Thanks Alan,


do you know if there is any way to prevent the CUCM or the VoiceGateway to send outbound calls on specific channels?


For instance, if I have a trunk where from channel 1 to 10 I have ONLY inbound calls and from 11 to 30 ONLY outbound I need to be sure that channels 1-10 won't be used for outbound.


Thanks


Lorenzo

Correct Answer
allan.thomas Fri, 04/30/2010 - 00:33
User Badges:
  • Blue, 1500 points or more

Hi Lorenzo,


My apologies, I made the assumption that you are using MGCP, can you confirm whether you are using MGCP or H.323? This is simply because with H.323 it is more flexible than that of the options you have with MGCP as I have already menionted.


Regards

Allan.

Biondilo Fri, 04/30/2010 - 01:10
User Badges:

We have CUCM 6.1 in MGCP with a Cisco 3845 VoiceGateway that has an E1 connected to PSTN. The Provider use the first 10 timeslots of the PRI for our incoming calls so we need to avoid utilization of that first 10 timeslots for the outgoing ones.



Another thing I can tell you is that a collegue suggested us to put the command "isdn negotiate-bchan" in the Serial x/x:15 VoiceGateway, but looking around about what command does I didn't understand how it can help to resolve my issue.


I know that via CUCM there aren't a lot of options to manage channels utilization so I looked at some configuration in VoiceGateway, like trunk-group configuration or other things, trying to block outgoing calls on the first 10 channels but I haven't enough experience..


Thanks

allan.thomas Fri, 04/30/2010 - 13:38
User Badges:
  • Blue, 1500 points or more

Hi Lorenzo,


As previously mentioned MGCP will not give the flexability that you are looking for here.  With H.323 it is possible to configure trunk-group(s) as you mentioned on each controller and logically group your PRIs into on trunk-group and prioritise them accordingly or define them within destinct trunk-groups for each dial-peer.  Your outgoing dial-peers can then be configured to use the appropriate trunk-group for your outgoing calls.


I can appreciate your predicament, however configuring or converting your H.323 gateway(s) from MGCP should not contemplated unless you have a sound understanding otherwise you may find troubleshooting difficult as essentially you are configuring your dial-plan on the gateway moving the control from CallManager.  You should look to engage a Cisco Partner if this is something that has a strong requirement to change or migrate your MGCP gateways.


Regards

Allan.

David Sandoval Tue, 09/21/2010 - 05:51
User Badges:

Hi Allan, I have a similar situation as described here, however, I am using H323 on my voice gateway and was wondering how can this be done if I just have 1 pri to the telco?


I would like to be able to reserve a couple of channels for outgoing calls only, when the call flow at the customer site is very high inbound.


Thanks,

David Sandoval

NuWave Technology Partners

Actions

This Discussion