We currently have VOIP system at work which is basically an 8 line/port FXS Telephony Gateway.
My boss would like to add an additional 4 lines to the system as easily as possible. However
The Gateway only has 8 ports

I rang up the phone company that installed the Voip system originally and he said that to go from
8 lines to 12 we would need to upgrade our entire system to IP PBX and would cost Approx $5,000

I call BS however I don't know enough about phone systems to be able to call him on this.

Logically I was thinking , can't I just go out and buy a 16 port Telephony gateway ? and problem solved ?

The average price on a 16 port is around the $2,000 mark, so I'm struggling to understand how this phone
guy can justify the extra $3,000 ? Can anyone shed some light on this for me

The transducer module on a 16 port telephony gateway cannot process the required data flow for adequate voice transmission. You were right in calling BS but, an IP PBX system is overkill for your application. Have a look at a QSIG system to bridge two 8-port gateways together in a lossless format. It uses the new H.323 protocol and operates very well over an IP based system. Failing that, you could even use a DPNSS to connect directly to trunk lines and use SIP as the broadcast protocol.

Thanks for the reply,

I'm doing as much research into this before I go mouthing off at the Phone guy. I thought IP PBX was going to be an over kill ! that bastard.
Isn't IP PBX designed for multi branch companies so they can connect their phone system over the net ?

All we need is 12 very simple lines so people can call out. Can all be the same number, we don't even need people to be able to call the number.

I'm struggling to get my head around what QSIG technically is its it firmware ? or just a source code ? .

"ISDN based signaling protocol for signalling between private branch exchanges in a private integrated services network" That whole description just
goes over the top of my head

Our very basic system is .

ADSL2 Modem connects to - Wireless-G 2.4 router which connects to the Linksys 8 Port telephony gateway.

So I gather I have to get our router to be able to connect to multiple Gateways at the same time ? If so QSIG is the solution
where do I add it to the chain which is our voip setup

update:

Well now I've pissed off our phone company. They sent the tech in this morning to install the New software
and after a very awkward 20 minute conversation of the phone with The Boss, the Tech and Me, the Tec left
a bit bitter. Sure I wasted his time coming out here and apologized. But these guys are trying to make me spend
$5,000 which I don't need to spend.

If anyone could shed some more light on my options please let me know asap