PRI sizing? any good ratios to start with?

[Tommer Catlin]

I know I should be going off Erlongs, and all that fun stuff.. but are their any industry standards for PRI sizing? For instance..

4 DIDs to 1 PRI Channel?

Thanks

[jneiberger]

You answered your own question: the industry standard method for determining trunk sizing is Erlang B.

http://www.erlang.com/link_traffic.html

[dgahm]

If you don't have the call data to perform Erlang calculations, you just need to take a SWAG, and adjust as needed. Ratios or rules of thumb are difficult because users are so different. An insurance sales office will need more trunks than a similar sized engineering firm.