Hi all,

After stalking this forum for several years I have finally got around to registering. Although trained as accountant I have spent the last 20 years handling IT and phone systems at almost every company I have worked for. I have participated or headed the installation or upgrade of Rolm, AT&T Definity, Nortel, NEC, and InterTel systems.

As my topic says over the last 20 years it seems that the line between key systems and PBX has blurred to the point where there is really no distinction anymore in terms of features.

Am I missing something? If there is a difference can anyone furnish a concise list of what puts a system in one category or the other?

Thanks and glad to be around such great experience and resources.

Todays key systems pretty much mirror the PBX's of yesterday, not much difference now.

what he said....

the seperation is more about service and a reliable vendor nowadays, than whether or not one system is better than the others. Not all systems are equal or exact, but the differences are far less now.

I would say, if anything, is size. Most key systems are not going to go over 1000 ports. Otherwise, not much. Although, I would have to say on the bigger systems we get things like true 90v ringing and the loop limits seem to be FAR greater.

I would pretty much "echo" what has been said...but the PBX environment does allow for features in the higher end..i.e; call centers, ACD etc; and is a little more flexible with hunt group programming and some of the features...Had a customer today who is interested in "time of day routing for coverage paths"..So in some area's you get a little more in a PBX environment but like everyone has said..the line between the two has narrowed considerably over the years....

...bob...

Traditionally, key systems were "squared"--a line appearance for every phone. The old Tie 2260 with 22 lines and 60 phones comes to mind. The PBXs were configured to have many more lines (trunks or circuits), tie lines, OPXs, one main console, departmental receptionist electronic phones...but the majority of the phones were single line 2500 sets. Everyone dialed a "9" to get line access or a code to get access to the other circuits.

However, as has been said, the many features of the hybrid systems have blurred those traditional lines. In the newer VoIP systems, there sometimes are PBX and KSU modes---but the differences are very hard to see from a programming and use standpoint.

Besides Key systems being "square", the difference also used to be as simple as to whether or not the system had "Trunks" rather than "Lines". If all users dialed "9" to make a call, the TelCo delivered the lines as trunks and charged more for them. Trunks were thought to have more CCS (traffic) on them and thus justified the higher rates. When Key systems were installed as hybrids, they were supposed to be registered as PBXs but that didn't last very long. I agree that today, size is the best answer, but I have to regress and say that if you are using pooled line access, you are classified as a PBX.

Awesome everyone, thanks for the great feedback.

Joe