Small Business IP-PBX Config Help

I’ve done some research, and I’m slowly beginning to get it, I think. But some expert advice would be cool. I would like to accomplish the following:

  • 4-8 line IP-PBX with call hunting
  • 1-line POTS integrated into * (backup just in case - unnecessary?)
  • 1 fax analog line (not * integrated; could also use as backup line?)
  • customized auto attendant
  • music on hold w/ custom message

Can I accomplish this with:

  • *@home on Raid 1 server
  • Digium TDM01B 1-FXO card for backup POTS line
  • 1 multi-line SIP phone for receptionist
  • 8-12 inexpensive single-line extension SIP phones
  • auto attendant rings directly to appropriate extension
  • 4-8 unlimited ITSP lines
  • 2 POTS lines (1 fax, 1 *-integrated backup analog line)

At what point (how many ITSP POTS-termination lines) would it be cheaper to go with a TelCo T1 vs an ITSP? Business VoIP plans cost $29-$49/mo for the first line, $12.99-19.99 each add’l with only 500 min. included.

Is it possible to have * route all incoming calls to the secondary lines and have all outgoing calls go out of the unlimited line? Further, if the outgoing line is busy, can * use secondary lines in a round-robin fashion to avoid exceeding the “included” minutes of just line 2? Also, can * set all numbers to show the CID of the main number on outbound calls so customers don’t call directly into a back line?

Any help on these questions would be GREATLY appreciated.