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New Member

Using BChannel on PRI Interface for DialOut

Hi Folks,

I have a cisco 3620 with a PRI interface (E1) and 30DM. I can configure the router to dialout to an ISP using one of the asynchronous modems in the pool.

I was wondering if it is possible to use a BChannel to make this call purely digital and instantaneous.

Whenever I do a show interface, I see the B Channels which come up as S0/x

I can obviously configure the D Channel but when I try to access a "B Channel", the router tells me "B-Channel not accessible or something like that" (sorry I forgot the exact term ... it's been two weeks).

Is it possible to grab a couple of B Channels and use them in a dialpool, and all that other related good stuff. I would love it if we could do this. Unfortunately, I don't have space to put Physical BRI' Interfaces on the router anymore, so if there is a way to plug into some of those B Channels, I would be very glad if you could show me your expertees.

Thanks for all your help and insight

Manish Hira



Re: Using BChannel on PRI Interface for DialOut

interface serial0:23

dialer pool-member 1 max-link 2

encap ppp

ppp multilink

interface Dialer0

ip address x.x.x.x ( or ip add negotiated)

encapsulation ppp

no ip route-cache

no ip mroute-cache

dialer pool 1

dialer remote-name abcd (if you know)

dialer string xxxx

dialer-group 1

no cdp enable

ppp authentication chap

ppp chap hostname xyz (login name provided by ISP)

ppp chap password xxx

ppp multilink

This gives you the option of using the B channels...the other end needs to be an ISDN interface to work.

Thanks, Makarand.

New Member

Re: Using BChannel on PRI Interface for DialOut


Thanks for the config info. I see what I need to do. My mistake was that I was trying to enter a specific group of B-Channels to make them part of a dialpool.

I never knew thought of trying to enter the dialpool command for the D Channel.

Thanks once again.

I will let you guys know when I successfully do this within the next few days.


Cisco Employee

Re: Using BChannel on PRI Interface for DialOut

All the b-channels will inherit the config from the D-channel..So configuring D-channel (interface serial x:23) is a way to configure the group of b-chans.

Now you can dedicate one of the PRI line (all the b chans) to be used when you try to dialout but you can't dedicate only certain b channels for that.

Visit the following url for that

You can use dialer profiles to dialout on the pri line but the b chans will be picked by the router in a random manner..

New Member

Re: Using BChannel on PRI Interface for DialOut

Hi Tejal,

Thanks for your help on this. I will definitely try and see if I can do this within the next 5 days.