Looking for general technical info in ISDN, PRI and the different type 4

[Snapper]

Need a quick lesson on the different types of trunking. PRI, BRI, ISDN, T1 whatever. Thanks in advance

Attitude is everthing.
-Snapper

 

[orypecos]

BRI is a two digital lines with one control channel.
T-1 is 24 channels in USA with one control channel or can have 24 working channels if using robbed bit. But if using robbed bit, can not be used for data.
PRI is 23 channels with one control channel(if u have many pri s , then they can share a d control channel, and u can use 24 channels for voice or data instead of just 23.

 

[NuggiFirst]

A little correction about PRI:

PRI also known as ISDN-30, can carry 30 voice/data-channels and one control channel (d channel)

I don't know is there's other PRI-configurations than this, but here in Denmark/Sweden a PRI has 30 channels.

 

[orypecos]

Some international areas can have more than 24 channels, but in the USA the limit by the federal governement is 24 channels if it us used outside of a private campus.

 

[IPGuru]

The North American & I beleve Japanise telecom networks use isdn @ 1.5Mbps circuits with 24 channels configured in various ways. Europe & most of the rest of the world use isdn@ 2Mbps this gives 32 channels - 30 for speach 1 for singnaling & 1 for synchronisation.

the stolen bit signaling system is why ISDN calls in North America are 56K rather than 64K

In the UK anolder BT proprietry system is also in use DASS II (Direct Access Signaling System V2) this is also 2Mbps with 30 channels for speach.

 

[chris13]

isdn-trunks at 1,5Mbps are called T1,
the other with 2Mbps E1

good sources to look at:

http://iroi.seu.edu.cn/books/ee_dic/whatis/dsignalx.htm

http://www.fact-index.com/t/t_/t_carrier.html

 

[ISDNman]

Just a clarification

In the USA a T1 has 24 64 kbps time slots. If 23 are left clear channel (the Bearer or B channeles) and one is used for ISDN signalling (the it is called a PRI.

Basically, the DS1 (T1) becomes Layer 1 for the PRI (also called 23 B + D)

In Europe and many other places they don't have T1, they have E1 which is the similar to our T1 but runs at 2 mbps and has 32 time slots (one reserved for sync). Similarly to the above, if you remove 1 time slot and make it a D channel you now have a PRI only it is a 30 B + D).

The D channel protocols vary, but generally speaking you'll see Euro ISDN according to ETS 300 on the 30 B + D (though there are some older National variants) and one of several different Bellcore and Proprietary protocols on the 23 B + D PRIs here in the USA.

Afain generally speaking expect A-Law on the E1 and 30 B + D and mu-Law in the T1's and 23 B + D PRIs.