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Change the pri-group timeslots for MGCP E1 port.


Hi ,

I need to reduce the number of pri-group timeslots to 15 which currently is 1-31 on the E1 port on the mgcp gateway connected to the PBX.

Current configuration in the router is as follows

ccm-manager mgcp

ccm-manager music-on-hold

ccm-manager config server

ccm-manager config

controller E1 0/0/1

clock source internal

pri-group timeslots 1-31 service mgcp


interface Serial0/0/1:15

no ip address

isdn switch-type primary-net5

isdn protocol-emulate network

isdn incoming-voice voice

isdn bind-l3 ccm-manager

no cdp enable

The reason is that I have a new PRI E1 on the same mgcp router to the PSTN and I am falling short of DSP's.




Steven Smith
Rising star
Rising star

I am looking for a doc on this. I will give it to you when I find it. You do not change the config in the gateway. There is a callmanager service parameter that allows you to only use certain channels on a pri. I am away from my CCM, but I will get the service parameter for you by monday.

As promised, here is the service parameter.

Change B-Channel Maintenance Status 1

It is an advanced parameter, so be sure to check advanced when you are looking for it.

Here is how it works.

S0/DS1-0@SDA123456789ABC = 0000 1111 0000 0000 0000 0001(24 bits for T1. Channel number begins with 1 to 24 from left to right. The last one specifies the D-Channel, which does not get affected. In this example, 5th-8th B-Channels are out of service).


S1/DS1-0@DLS2-CM136-VG200-2.SELSIUSCMLAB.CISCO.COM = 0000 0000 0000 0000 0000 0000 1111 1111(32 bits for E1. B-Channel number begins with 1 to 32 from left to right. The 16th channel specifies D-Channel. The last bit does not affect any channel. In this example, 25th-31st channels are marked out of service).


The Device Name as specified in the Gateway Configuration page in Cisco CallManager Administration MUST exactly match the gateway name that this field specifies. To avoid any manual inputting mistake, copy the Device Name from Cisco CallManager Administration and paste it into this service parameter. “=” is mandatory and unique to distinguish the Device Name and BChannel Maintenance Status fields. BChannel Maintenance Status = xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxxx

Where x can be

0 -- In service

1 -- Graceful out of service (Change channel status until active call ends if an active call exists on that channel.)

2 -- Forceful out of service (Tear down active call first; then, change channel status immediately if an active call exists on that channel.)

Because values other than 0, 1, or 2 are invalid, the system ignores them. Make sure that the total number of ‘x’ is either 24 for T1 or 32 for E1. Any other invalid length or mismatch (for example, 24 for E1) gets treated as error, and no action gets taken for that device.

SPACE: Optional.

The spaces between device name and '=', between ‘=’ and BCHANNEL MAINTENANCE STATUS, and between x and x, are all optional. You cannot use any space inside the DEVICE NAME field.

To use this feature, ensure that the Enable Status Poll flag on the Gateway Configuration page is checked and updated; then, the gateway must be reset for the first time. After this, changes to the service parameter will take effect without resetting the gateway.

Maximum length: 255.

is there a way of having more than 5 "change b-channel maintenance status" entries

No - the maximum is 5 for this.

If you have more than that you would have to look at using H323 instead of MGCP.



Aaron Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!

And why wouldn't this work by changing it in the gateway? Or is that just a "not reccomended" solution?

I'm interested in this, as I have some DSP resources to balance between two E1 controllers, and I just changed the config in the gateway :)

If you are using mgcp backhaul to the ccm, changes in the gateway are not effective. You can try to busy out a channel, but it will not work. You have to make the change in CCM.

How will SRST work with this type of config?


Hi. It is possible to use only 15 timeslots in the GW itself with the following config:

pri-group timeslot 1-15,16 service mgcp

You just MUST NOT TO configure the ccm-manager config command.

it is working good but it is not supported by the TAC. If you use the CCM with the B-channels... i am not sure that working good and in SRST mode the mgcpfallback will switch back to full timeslots...



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