Stephen Bosch
2007-May-10 11:02 UTC
[asterisk-users] Polycom power over ethernet (PoE) cables for 500/501, 600/601 and 650 sets
Hi, folks: I just took delivery of new PoE cables (PN 2200-11077-002) for our Polycom phones here in the office. I have the following to report, for the erudition of existing Polycom users and those considering purchasing Polycom sets from the set of models noted in the subject: 1. The cables do indeed work (hooray). 2. The cable has a module on it about a third of the way from a female end. The module is about the size and shape of a large cigarette lighter or a small bar cellphone; it has a green LED indicator on it, which illuminates when the connected device is drawing power. The module also has a receptacle for the DC end of a Polycom power adapter. Presumably these cables can replace the default external AC injection cable completely. The module, for those who are interested, provides ground-loop detection and protection. Early revisions of the 802.3af standard did not provide for ground-loop protection in the midspan, and so phones would overload (and fry) PoE midspans (this is strong evidence that there were no telecom engineers in the 802.3af working group, since ground-loop protection has been a necessary part of PSTN systems since the dawn of time). I suspect newer midspan equipment is not burdened with this problem, which would explain why some people can use garden-variety cables with these phones on PoE. 3. I thought I might save some clutter by putting these cables between the midspan and the patch panel, but then I discovered that the male end of the cable is keyed, just as in the default AC cables provided with the phones, meaning that they'll only work if plugged directly into the phone itself. The reduction in clutter with this set-up is, unfortunately, not what I had hoped, though anything is better than nothing. I imagine it would work if I sanded away the plastic post on the connector, but that says nothing about how it might behave if a non-compliant device were plugged into it. Better safe than sorry. Cheers, -Stephen-
John Marvin
2007-May-11 01:35 UTC
[asterisk-users] Polycom power over ethernet (PoE) cables for 500/501, 600/601 and 650 sets
Stephen Bosch wrote:> > 3. I thought I might save some clutter by putting these cables between > the midspan and the patch panel, but then I discovered that the male end > of the cable is keyed, just as in the default AC cables provided with > the phones, meaning that they'll only work if plugged directly into the > phone itself. The reduction in clutter with this set-up is, > unfortunately, not what I had hoped, though anything is better than > nothing. I imagine it would work if I sanded away the plastic post on > the connector, but that says nothing about how it might behave if a > non-compliant device were plugged into it. Better safe than sorry. >Actually, I did exactly this with the default AC cables. I plugged my Polycom wall warts into my UPS near my household patch panel, filed off the tabs on the AC cables and used them as patch cables between my (non POE) switch and the patch panel. I use a standard patch cable for the phones. I don't think this would be a good idea for an office environment. I'm not sure what would happen if I plugged something other than one of my Polycom phones (501's) into the non standard powered ethernet jack. I'm fairly safe in my home environment, since I am usually the only one messing with ethernet cables in the house, and I have told my family specifically not to ever unplug one of the phones in order to plug in something else (they can always plug into the back of the phone instead if they need a temporary connection). John