Question about power over ethernet injectors?

Not sure if this is the best forum for this, but I want to get Cisco IP phones to use with Asterisk. All the ones on eBay do not come with power adapters as they support PoE. I just have a few questions, first one is if I just have a normal network with switches and so on, what’s required to enable PoE on the phones? Is it just a special switch that plugs into the wall that does it?

Was reading about PoE injectors which seem to do that, but it’s not really clear if you need a PoE injector for every device, or if just 1 is needed or what. Am I better off just buying 5-10 power adapters for all my phones instead? Thanks!

The diagram on this image confused me since it looks like only one injector is used, but then they have a PoE router…


That looks so dodgy and I doubt it wil be UL certified, Cisco Sets can use a standard POE midspan injector or a POE Swirch such as a netgear. But some require a specific Cisco POE injector.

To be perfectly honest you will be better off buying a Aastra or Polycom set ,as unless the set you are looking at is one of the newer Linksys(cisco) sets , you will have to upgrade the firmware to make it work with sip, and if that goes wrong you will have a very expensive doorstop


Thanks for your help. I was actually looking at ones like these on eBay, it says it’s been updated to SIP and ready for Asterisk. Most on eBay seem to say that so that’s why I was thinking it wouldn’t be too hard. I don’t mind buying power adapters if necessary, just wasn’t sure if it was less expensive to get a device that provides PoE versus buying 9 Cisco power adapters. … 658wt_1078