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Which Really Uses the Most Power?

After my previous post, which compared power demands for TDM and IP phones, Eric wrote me and asked, "Doesn't an IP-PBX on a server draw less power than a TDM PBX? Is this outweighed by the multitude of phones?" The bottom line is: IPT is good, TDM is better and Hybrid is Best for power--- to a certain port/device size.

After my previous post, which compared power demands for TDM and IP phones, Eric wrote me and asked, "Doesn't an IP-PBX on a server draw less power than a TDM PBX? Is this outweighed by the multitude of phones?"

The bottom line is: IPT is good, TDM is better and Hybrid is Best for power--- to a certain port/device size.First- there really aren't Energy Star servers since the standards for them aren't completed (Last I heard- but Gary Audin may know differently)

Second- The (IPT) server takes MORE juice than a Hybrid, which only requires 210 WATTS and I can power 200 devices and actually more like 300 with a cool feature. (210 WATTS)

The TDM, say a large Norstar Modular with FIBER not copper- I can run close to 200 phones and PRI and T1 and some POTS and get by around 600-700 WATTS.

But once you take the phones into consideration, the TDMs are still more efficient than IPT (depending once again upon the configs). Worst case 600-700 WATTS for a Nortel Norstar MICS vs. 1,000 WATTS for 200 IP phones and how many WATTS for the server?

Now, I'm comparing the SMB space. The server does win on the bigger systems- but once you figure 6 WATTS per phone times 1,000 phones = 6,000 WATTS X 24 X 365 / 1000 = kWh used. The server in this space will have double or redundant power supplies, fans, RAID 5 or better and a bunch of other gizmos. Nortel's old Option 11 and even their other wares would come close if not less than the IP server + IP phones. What gets them is the separate voice mail box (chassis). Or, OCTEL- yes, the IP phones would offset the power in these cases- but it's a real challenge getting power boosted to all those closets and upgrading the UPSes in those closets which means now we will have more heat.

The box changed a little (PBX) while the accessories- voice mail/AA changed a whole lot. Nortel went from just the old voice mail systems using 300-700 WATTS for them to just under 50 WATTS and that's a fully licensed voice mail/AA only-- Panasonic and the others did the same thing--- they all shrunk the voice mail/AA to a cheezy little cabinet or shoe box size using Flash Drive technology and stuck a web browser on it which appealed to the masses. So- TDM is a long sliding path of improvement.

There's also that OLD argument that TDM was fat - dumb - and happy with no improvements in the technology. That isn't true.

But getting back to power--- TDM for the masses is better (+90% of the telephony market is SMB/E) than IPT with the exceptions I noted.

Over the years, the TDM boxes got very small compared to the 1980's generation of systems which were large refrigerators standing next to one another, then by the early 1990's the footprint shrunk significantly to small cheapy refrigerators (the size) that teachers have at school for example. So shrinking the footprint in the 1990's era meant less space for facilities/real estate to deal with for voice. That was a big deal back then.

So it really depends but in large configs- the voice mail box and other external systems running applications such for voice but needing the "external processing power"- then, yes- the server (IPT) and IP phones will offset the power and come out better.

In 2000 we sold an IP-PBX to a commercial real estate firm in Bethesda, MD- they had a ROLM CBX II---they loved me for knocking out the 220V connections and then running their company on a puny rack mount box. Their power savings and air conditioning and the room- that was now leasable space, previous to IPT it was not.