| Do you remember when the power went out at your | | | | Instead, each IP telephone installation required a data |
| house, and the phone still worked? The reason is that | | | | jack and a power outlet. |
| the phone company sends very low voltage power | | | | In order to do away with local power requirements, |
| over the telephone line. This power is separate from | | | | some manufacturers implemented proprietary |
| the electric company's network, so even if the power | | | | methods to send low voltage power over Ethernet |
| goes out at your house the phone will still function. | | | | lines. Others provided midspan power units that were |
| The same principal exists for business phone systems. | | | | installed in front of current data switches to add power |
| Manufacturers of these systems provide standards | | | | in series. The Institute of Electrical and Electronics |
| for sending low voltage power through the extension | | | | Engineers (IEEE), one of the world's leading technical |
| ports. This power allows for the extensions to have | | | | professional societies, ratified the 802.3af Power over |
| features like backlit displays, general functioning, and | | | | Ethernet (PoE) standard in June of 2003. The 802.3af |
| ringing. In some cases, consoles with large displays or | | | | PoE standard allowed network hardware |
| telephones with adjuncts like speakerphones do | | | | manufacturers to produce switches with integrated |
| require local AC power. However, the majority of | | | | PoE support. Manufacturers of endpoint devices like IP |
| extensions use line power. | | | | telephones, wireless access points, and IP cameras |
| Enter the era of IP telephony. IP telephones run over | | | | could now produce compatible devices as well. |
| your company's data network. The same LAN cabling | | | | As 802.3af PoE became more popular, most |
| that connects your data equipment (servers, | | | | proprietary standards fell to the way side. Today the |
| workstations, etc.) also connect your business IP | | | | majority of IP PBX and IP telephony manufacturers |
| phones. In theory, IP telephony systems are just | | | | have adopted this standard. This is great for the |
| another application running on your data network. | | | | consumer because prices for this technology have |
| An early concern with devices like IP telephones was | | | | dropped significantly. Entry level consumer PoE |
| power. Ethernet standards never included | | | | switches can be found between $350 and $600. |
| requirements for power on cabling. The switches in the | | | | Although most IP telephones support both 802.3af PoE |
| network room, your workstation computer, and your | | | | and local power supply options, it now makes sense to |
| company's servers all have local power supplies that | | | | change your old switches to units supporting PoE. |
| plug into an outlet. The first IP telephones that were | | | | Consider this: Typical IP telephone local power supplies |
| released came with local power supplies as well. | | | | cost between $19 and $29 each. If you multiply this by |
| Because businesses typically deploy more phones | | | | 24 phones, then you are well into the cost range of a |
| than data equipment, provisions for power outlets at | | | | new 24-port switch that supports PoE. For the |
| each installation site had to be made. This proved to | | | | cost-conscious business owner the answer is clear. |
| be more difficult than traditional installations which | | | | You can now make the switch to PoE and save. |
| simply involved plugging the phone into the jack. | | | | |