I got our geographically spread company onto Aptela and it was almost perfect, except for quality (likely because of their growth)- they allowed plenty of options, they provided software, apps, and web client that was all intuitive, good support, etc. They were purchased by Vocalocity which has been a real pain in the ass about a few things. Their support is so-so. That being said, they are still probably better than most of what is out there. Their system does work and we do not have quality issues anymore, and they have pretty much any feature you would want. They have all the apps and such, but not quite as intuitive from an admin prospective. I can't remember offhand, but we have between 15 and 20 lines (mostly unmetered), virtual receptionists, etc and we pay around $500/mon. I would get a nice bit off our bill if I refer you, so if you want to talk to them, send me a PM or something and I'll set you up.
Either way I'd recommend a hosted solution unless you want all the extra work and stress and a huge upfront cost.
