Hey LAS, I have been using an Asterisk distro called Elastix. They are fully GPL 2.0 and the development is current. Takes a lot of work out of setting up a usable Astrisk server. http://www.elastix.org/index.php/en/
If you have a half-way decent IT contact, have them setup your own PBX server and SIP trunk. This method will offer you the lowest recurring prices by far, in exchange for some upfront configuration costs. SIP trunking through Broadvoice will cost you about $50/month for unlimited extensions and up to 5 concurrent calls. A server can be anywhere from free (in the form of a repurposed computer) to no more than $200 (nothing fancy, it's a no-frills linux machine).
On the server, you'll need (http://www.elastix.org/en/)[Elastix], an open source PBX appliance. Your IT contact will be able to learn how to use Elastix very quickly, and with it, he will be able to set up auto-attendant, forward to mobile, parking lots, custom messaging, and basically anything you can imagine at no additional cost.
Elastix and Boradvoice can also scale with you seamlessly. Elastix can support anything from small offices to regional multi-tennant telephony providers with thousands of simultaneous users. Eventually, Broadvoice won't be a good financial decision, and you will need to switch to something like OnSIP or Flowroute and get a metered plan.
Is it Elastix? I'm using this. It's a distribution that uses Asterisk and FreePBX, it's also built on CentOS. It's pretty easy to use. I think I used a different PBX previously when I tried it with my Google Voice, but IIRC you just need a plugin for FreePBX.
I didn't have any problems with Google Voice. Actually it's pretty fun to put an IVR in front of it.
You could try this u/ChrisLAS, Elastix: Open Source Unified Communication Server. http://www.elastix.org/index.php/en/ Also a Youtube video talking about sending Voicemail recordings to an Email. https://www.youtube.com/watch?v=PDq1LdXAd14#t=11m20s
Check out elastix. The software is free but they will sell you a hardware appliance already loaded. It's Asterisk with an embedded modified version of freepbx on top. You can add a four port fx0/fxs card to grab the analog phone lines but the entire setup is voip/pc based. Pair it with some grand stream phones and you can auto sync google contacts directly to the phones. We use it as a nice little solution for small offices that don't have the bandwidth for a true voip solution.
I have Elastix: http://www.elastix.org/ It's running in a VM, it's basically Asterisk/FreePBX with some extras running on -- I think a CentOS build of Linux. For the trunk at home I just used my Google Voice account.
I mainly use my Android phone with c:sip softphone client or some others, but I've used several physical Grandstream phones and they all seem to work fine.
I used Elastix (http://www.elastix.org/index.php/en/) with a card interfaces between phone system and computer. I've also had a VOIP system (through these guys: http://www.gradwell.com/) that does all that, there are tons of people who can do it.
VOIP is pretty exciting, because you can have local phone numbers from all over the world going to wherever you are ....
Hey I setup a custom VOIP box for a small business which I'm currently upgrading now. It's using Elastix for the VOIP software on top of CentOS for the OS. We're using Flowroute for SIP. Phone bill was over $300/month and is now down to under $30/month with significantly more functionality than they had before. The server is running on an old laptop and we're using Polcyom IP550 and 650 phones.
Since you're looking for something easy to setup I'd go with a hosted service. I never came across any that I really enjoyed. Used RingCentral with a client but was dissapointed.
What POS system is that? Lemon?
The 2 big things I have seen in businesses is http://www.elastix.org/ in conjunction with audiocodes stuff. It has all the applicable business support and training anyone would want.
ClearOS is the other big one because it's just as epic. http://www.clearfoundation.com/Software/overview.html
The even bigger thing is that rebranding these is super easy. So you can become a reseller very easily with elastix and clearos doesnt even need a partnership.