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Beginner

## Request calrification on T1/E1/PRI

Dear Experts,

1)I have configured many E1 implementations so far. But today while preparing for my CCNP i got this confusion. We use an E1 card for connecting a PRI. But i read E1 and PRI or different!

2)DS0 means Cas, Pri means CCS signalling, then for T1, E1 what we would use?

3)In a T1 we get total 24 channels, if we use CAS then we get 24 channels, and with CCS we get 23 channels. But for E1, when we use CCS we get only 30 B Channels and 1D channel, where as the 32nd Channel?

Kindly consider this as my learning and help me!

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Collaborator

## Re: Request calrification on T1/E1/PRI

Hi Sampath,

1)I have configured many E1 implementations so far. But today while preparing for my CCNP i got this confusion. We use an E1 card for connecting a PRI. But i read E1 and PRI or different!

2)DS0 means Cas, Pri means CCS signalling, then for T1, E1 what we would use?

T1 and E1 are classified based on the geographical locations. In countries like U.S, we get only T1 lines from them and in places like Europe, India we have E1 lines. If you simply tell E1 then you mean a E1 CAS and if you configure the E1 line with CCS, its called E1 PRI.

3)In a T1 we get total 24 channels, if we use CAS then we get 24 channels, and with CCS we get 23 channels. But for E1, when we use CCS we get only 30 B Channels and 1D channel, where as the 32nd Channel?

With T1 PRI, you get 23 B channels for data/voice and one D channel for control

With E1 PRI its a bit different, there is a one separate channel for control and one for signalling,

So with E1 PRI, you get 30 B channels for data/voice, 1 for signaling and 1 for control messages.

HTH
Rajan
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6 REPLIES 6
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## Re: Request calrification on T1/E1/PRI

To clarify things:

ISDN runs on top of the T1/E1 circuits. There are two types of signaling:

- CCS : Common channel signaling (it uses a dedicated DS0 channel for the signaling)

- CAS : Channel Associated Signaling (it uses the data channel for signaling)

Now, PRI is an interface standard used on ISDN in order to carry multiple DS0 channels.

With this in mind:

- E1 PRI with CCS = 30 B channels and 1 D  channel
- T1 PRI with CCS = 23 B channels and 1 D channel
- E1 PRI with CAS = 31 B Channels
- T1 PRI with CAS = 24 B Channels

Georgios
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Beginner

## Re: Request calrification on T1/E1/PRI

Hello,

So on a T1 PRI, you get 23 B channels for data/voice and one D channel for control.

If there are 46 PRI channels needed does that mean 2xT1 channelized ports are needed for the device?

Ton

Collaborator

## Re: Request calrification on T1/E1/PRI

Hi Ton,

yes, that is correct. YOu need 2XT1 ports to terminate two T1 connections to get 43 B channels

HTH

Rajan
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Beginner

## Re: Request calrification on T1/E1/PRI

Hi Rajan,

Did you mean 46 B channels? If it's 43 then additional T1 would be needed.

Ton
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Collaborator

## Re: Request calrification on T1/E1/PRI

Hi Ton,

My bad, yes 2 T1 PRI connections can provide 46 channels in total.

But why you need additional T1 for 43 ? 2 would be more than enough

Thanks

Rajan
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Collaborator

## Re: Request calrification on T1/E1/PRI

Hi Sampath,

1)I have configured many E1 implementations so far. But today while preparing for my CCNP i got this confusion. We use an E1 card for connecting a PRI. But i read E1 and PRI or different!

2)DS0 means Cas, Pri means CCS signalling, then for T1, E1 what we would use?

T1 and E1 are classified based on the geographical locations. In countries like U.S, we get only T1 lines from them and in places like Europe, India we have E1 lines. If you simply tell E1 then you mean a E1 CAS and if you configure the E1 line with CCS, its called E1 PRI.

3)In a T1 we get total 24 channels, if we use CAS then we get 24 channels, and with CCS we get 23 channels. But for E1, when we use CCS we get only 30 B Channels and 1D channel, where as the 32nd Channel?

With T1 PRI, you get 23 B channels for data/voice and one D channel for control

With E1 PRI its a bit different, there is a one separate channel for control and one for signalling,

So with E1 PRI, you get 30 B channels for data/voice, 1 for signaling and 1 for control messages.

HTH
Rajan
Pls rate all useful posts by clicking the stars below