We are considering this, and I'd be happy to pass you on to the outfit we've been using as "broadcast integrators". Don't think the listserv allows commercial references.
The biggest issue with voip for all your lines is to be sure
you have a good enough (both stability and speed) internet
connection to support it along with your other bandwidth
Also if you're using something like Comrex or Tieline over a
POTS line, this won't work on a voip line.
From a quality standpoint having worked with both voip and
POTS, the POTS line usually sound better - especially if
you're putting the calls on air. But on the other hand if
you have someone calling from a cell phone (or a voip line)
into a POTS line, you can run into similar quality issues.
Most people seem to be fine with the slightly lower quality
of a voip call.
Also with VOIP there is usually a little bit of audio delay
when compared to POTS. But then you can have slight delays
with cell phone calls too.
From a reliability standpoint POTS is still overall more
reliable then VOIP, but that may not be an issue.
On the plus side - VOIP can save a lot of money. There are
some services that offer VOIP accounts for little to no
cost, and DID (dial in direct numbers - traditional phone
number service) for $5/month (and sometimes less).
Depends on what are trying to do. for that budget looks like you are putting in a KSU (a voip box) As Lorne points out, you need to have a quality internet connection to reduce latency and jitter. You probably don't need to go with setting up a PBX and will find lots of companies that offer virtual PBX, so you would only need the phones. I do know from experience, the audio quality is very good using our current provider.. much better than conventional POTS service using the G711 codec.
Over at CKNN in Bella Coola, I just setup something for them that you might find interesting. They use a fancy cisco phone from Iristel. it is a VOIP phone service, acts like a regular POTS phone, but much higher quality. For the price of a conventional landline, you get a phone will unlimited calling in Canada. Toll free 800 numbers are inexpensive.
Nuxalk Radio are using a neat little device that plugs inline with the handset. It gives a signal to the board for both the caller and DJ. Works with VOIP and Analog POTS phones.
At CJUC in Whitehorse, we use Iristel also, multiple lines, toll free and a cool feature we added recently, a POPVOX number that callers leave messages and then the recording is turned into a mp3 file that gets played by our automation system into automatic rotations.
check out http://cjucfm.com/speakers-
CJUC would love to hear from other stations and call outs, give it a try at
www.iristel.com and their group has packages for Canadian radio stations requiring multiple lines, back door numbers, hosted PBX,etc, etc
Iristel sponsors our station and supports us in so many ways. A big supporter of community radio. Thank-you.
BTW If you have a bunch of money to blow or are interested in really cool technology merging Telephony and AOIP, check out Telos Alliance. Telos are the ones that manufacture CJUC's new digital audio board.
The one thing with Skype - and I admit that I have not
checked the terms of service in a while so this may no
longer be an issue - but it used to be a violation of the
Skype terms of service use to put a Skype call on the air.
I do recall several years back there were incidences of
radio stations receiving "Cease and desist" letters from
Skype lawyers over this type of use, but I have not heard of
any such situations in recent years.
Anyways, just a word of caution - and it may be that the
EULA has changed since then.