CCIE Voice Lab Blog

PRI Channel Selection Order

I sometimes get confused as to which order to have the channel selection when configuring a PRI, be it MGCP 6608 or otherwise.

TOP_DOWN (first to last) or BOTTOM_UP (last to first). If you are not sure which port order to use, choose TOP_DOWN.

ASCENDING order (channel 1 to channel 23) or DESCENDING order (channel 23 to channel 1).

TOP_DOWN = ASCENDING
BOTTOM_UP = DESCENDING

To minimize glare conditions on the Telco circuit it is almost always recommended to configure the gateway opposite of what the telco is passing.