We have about 8 incoming PSTN lines that are currently on an old and antiquated Nortel Meridian ICS system. This system has been giving us some grief. We're looking for a new VOIP solution. I've been looking at a Cisco solution and it does seem pricey but I'm sure effective. Unfortunately, we probably can't afford a Cisco Unified Communications 520 which seems to be the ideal solution. We have about 15 people who need an extension and voicemail. We really don't have any need for a fancy system just an auto attendant of some sort when people call us.

It looks like we'll have to get an older router and an addon card for what we're looking for to get best value pricing. However, I don't know a a lot about Cisco voice products so I'm a bit lost as to what to get. The only thing I am sure on is the pricing on VOIP phones which we expect to be about ~$100-200. However, I'm not sure what pieces of VOIP infrastructure to get. Any advice?

I am familiar with Asterisk but right now I'm looking on pricing concerning a Cisco solution.