[asterisk-users] Asterisk dimensioning

[voip crazy]

Hello all,

I need to install asterisk for 900 sip users with 2 PRI ports.
It is posible to handle this number of calls/extensions with only one
asterisk machine?
Which is the best way to install that? two asterisk with openser. One
asterisk with openser .....
Is it necesary run a SER server on this enviroment?

Any clue will be welcomed.

Thanks in advance.

VoipCrazy