T1 electrical specs

[franke]

Does anyone know what voltages (ac/dc) and currents one should expect on a T1 circuit at the smart jack?

thnx
franke

 

[hawks]

-135VDC If i remember correctly

 

[franke]

Thanks hawks, do you recall if that is across the pair or to ground?

franke

 

[SYQUEST]

Hawks is close, if it is a "wet span". Seems most telco doing copper are provisioning HDSL for T1/DS1 and what the customer gets is a "dry span". Telcos stopped looping thru customer stuff in the late 1980s when the FCC allowed some network changes in the way Telcos handed off and DEMARCed hi-capacity services and for maintenance.

So from the Telco side you will see those voltage levels, but they are used to power and terminate the NIU.

If you want more specifics get a copy of one the manuals for WESTELL's T1 NIUs or ADTRAN's HDSL HTU-R NIUs. They list some of the specs about this type of hardware and the way the circuits are made up.

Hope this helps!

....JIM....

 

[franke]

Thanks Jim, that explains the discrepency. I'll check those 2 sites.

franke