atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's Just curious

What exactly is the difference between a T1 and a PRI. I know that you can't split voice and data on a PRI and you can get caller ID name and number but other than that whets the diffrence?

Sure you can split voice and data on T1 or PRI. PRI is just a over grown ISDN line.
ISDN is 2b+d and PRI is 23b+d. The d channel usually the 24th channel is flowing info all the time. There are several systems using the PRI technologies to do Qsig networking.

Thanks, in all my years in this business I have never put in a PRI. T1's up the ying yang but never a PRI.


[This message has been edited by dtmf (edited January 13, 2003).]

they are a little more tricky to program, but they do offer Caller ID and were typically cheaper than a standard T-1, but with all the new CLEC's now, that may not be the case. In some cases, you need a special T-1 card or software enabler in order to configure your system for PRI.

DTMF,
I would like to add to the above,each T1 circuit consists of 24 channels ,each channel is 64 kbps,which is composed 0f 8 kbps for signalling and 56 kbps for data transfer,thats means that the maximum data transfer per channel is 56 Kbps,on the other hand the PRI circuit consists of 23B+D ,each B channel is 64 kbps and you can that all for data transfer,because all the signalling and the controls done over the D channel 64KBps.Another very important thing is when you have a more than one application over the T1 for example you want to send data and voice ,you have to predefine the bandwidth that you want to use for data and for voice i.e.16 channels for voice and 8 for data,then you have to drop these channels using CSU/DSU with a drop and insert capability.on the other hand for PRI service they have CALL BY CALL,thats means that each call treated differentely if you want to make a voice call you will use one channel,if you want to make video call(video conference) you will use more than one channel ,whatever bandwidth you require for that call,if you want to send data is the same thing you will use whatever bandwidth required for that call,and after its finished you still have all the 23 channels available for voice or any other application.that just some of the benfits or features,If you would like to read some more you can visit my website www.samhassan.com ,under telecommunication there is alot more to read.