T1/E1 leased line and ISDN PRI

[global_biz]

Hi,

I have a little confusion about T1/E1 and ISDN PRI.

Document says T1/E1 is a leased line, and ISDN PRI is circuit switching.

ISDN PRI——（23B [64 kb/s] +D [64 kb/s] +synchronization [8 kb/s]）- 1.544Mb/s
ISDN PRI——（30B [64 kb/s] +D [64 kb/s] +synchronization [64 kb/s]）- 2.048Mb/s

The question:

Is "ISDN PRI (23B+1D)" = T1?

Is "ISDN PRI (30B+1D)" = E1?

Is "ISDN PRI" also a leased line?

Please help, thanks.

[Rajan]

T1/E1 usually refers to T1/E1 CAS (CHannel asociated signaling) in which the signaling is sent along with data in all the channels whereas PRI is CCS (common channel signalling) where you have a dedicated channel for signaling alone.

HTH

Rajan

[Rajan]

Rob has extensively explained the same in the below discussion:

https://supportforums.cisco.com/discussion/10041911/t1-cas-vs-t1-pri

[Rajan]

So BRI as suresh mentioned is for home and small enterprise.

BRI - 2B + 1 D channel

T1 PRI - 23B+D channel

E1 PRI - 30B + 1D channel

Normal t1/e1, there are no separate D channels for signaling and all the channels will be used for signalling along with data 

[global_biz]

Is the answer of "Suresh Kumar" wrong?

There are two types of T1/E1:

1). Normal T1/E1 for telcommuncation?

2). ISDN PRI T1/E1 for ????

[Rajan]

No. Suresh mentioned that t1 and e1 are types of pri. which is absolutely correct.

I want to add few more info to that.

BOth normal t1/e1 and pri can be used. only the way it operates is differenr. WIth PRI, you will lose one channel for carrying data as it will be dedicatedly allocated for signaling. 

[global_biz]

Thank you all, now I have understood the difference.

[Suresh Hudda · Accepted solution]

Yes, you are correct:

T1 has 23b + 1d, and E1 has 30b + 1d. In ISDN, there are two levels of service: the Basic Rate Interface (BRI), intended for the home and small enterprise, and the Primary Rate Interface (PRI), for large organizations, and E1 & T1 are two types of PRI.

Suresh