Yeah, you'll see this type of question out here on the forum a few times... unfortunately there is no hard and fast forumla you can plug in and use. It really does depend on how the site is going to use the system.
1. Are they using Unity as an auto attendant (i.e. all incoming calls to the company are fielded by Unity)? If so, you'll need to budget more ports.
2. Are most of the subscribers using desktop messaging for getting their voice mail? Are they using TRAP or their soundcard? If it's the later you can go lighter on the ports.
3. Is the system simply going to be voice mail only (i.e. DID lines that roll over to voice mail) or will it also be handling audio text applciations (i.e. trees of call handlers callers can navigate through to get information). This will require more ports.
Basically you're going to have to ballpark it after getting a feel for the customer what they want to do and then check back and "adjust" if necessary. This is what the port traffic reports are for, you can see how close to the bone you're playing it and if more/fewer ports are needed.
Off the cuff, 300 users will typically need 24 or thereabouts, 32 if they're doing auto attendant possibly 40 if they're doing heavy audio text/auto attendant and have phone only access to messages. That's a place to start anyway.
Jeff Lindborg
Unity Product Architect/Answer Monkey
Cisco Systems
lindborg@cisco.com
http://www.AnswerMonkey.net (new page for Unity support tools and scripts)
