[Asterisk-Users] Asterisk PBX and backup Circuits

[Rich Adamson]

> I am interested to know how one would calculate the amount of PSTN
> connection needed for backup on an Asterisk PBX that is being setup to
> receive its DIDs via a VoIP provide.  To sum up what I am
> implementing:  I am porting my DIDs to a VoIP provide so I will need a
> back up plan in place if the Data network fails.  In addition, 911
> will always be going out the PSTN so I know I need at least one POTs
> circuit.  Calls inbound and outbound will always routed through the
> data network.

In telco terms, you probably need to do a small Traffic Study; analyze
the existing traffic for maximum number of simultanous calls, etc.

If this is an existing business with an existing pbx, there are likely
some usage statistics available within the pbx. If that's not available,
"some" telephone companies will do the traffic study for you (don't
need to tell them why your doing it, but rather to determine the
number of telco lines needed for the business.) If that's not possible,
ask the telco to provide you with a list of "all calls with detail"
and run through the list to calculate the maximum number of
simultanous calls.

If this is a new installation with absolutely no history, your only
option is to guess at the maximum.