It seems that a mixed VOIP solution makes some sense for my small business situation. I've looked around to try and get quotes from capable people, without a lot of luck (Dunedin based). So far one lack of response to a written quote (following a verbal 'no problem' discussion), and another high priced quote that hasn't responded to a question of mine since. I was hoping to get someone local so that support would be more face to face, but that seems to be a hard ask.

We currently have an older pbx that we inherited with the lease, but it's full now on incoming lines (three), and internal extensions (six).

I'm reasonably capable (programmer, sysadmin, can do many things, master even less - linux/sbs server/php/perl/cfm/sql/exchange/postfix) but I've never dealt with VOIP. I'm sure given time I could get a solution that works, but I'm running out of time, with other projects happening at the moment. 

Ideally we want to keep the three analogue lines, and add VOIP for outgoing, adding internal extensions. No voicemail, no DDI, caller id would be nice, but no other complicated features.

So the question - how hard would it be to roll out a Cisco 320 system? It's hard to see what's involved, what the config would be like. Does the Cisco kit enable relatively easy assignment of features? Glancing at asterisk it looks far beyond what would be wise for me to look at. 

I guess I don't know, what I don't know. Any input appreciated.