Power Over Ethernet
Q: What is POE and why should I use it for my VOIP phones?
A: POE, or Power-over-Ethernet, is a means by which to power compatible network devices, in this case your phone. Unlike older digital telephone technology, where the phone requires no power or power is supplied from the phone system, all VOIP or SIP phones require power. This can be accomplished by using a power adapter that plugs into a surge protector or if necessary straight into the wall outlet.
Another way to provide power to the phone is by using a POE network switch. If you are placing more than 4-5 IP phones in your office I would recommend the POE switch.
The perks of POE are: 1) Placement of the phone is not restricted by an available electrical outlet. 2) A POE switch can be plugged in to a battery backup or UPS that will keep the switch up, in turn keeping the phones powered, during power surges, drops, or outages.
Q: What type of cabling do I need to have for a VoIP Telephone System?
A: CAT5e or Higher. CAT5e short for Category 5 Enhanced, Cat5e standard provides performance of up to 1000mbps (1000 megabits or one gigabit per second) and can be used up to a maximum length of 328 feet. This type of cable is used in structured cabling for computer networks, telephony, and video.
Reuse of existing cabling
Q: I have heard that Category 3 cable is rated at 10mbps and a VOIP call really only needs around 100K. Can I re-use my existing category 3 cable for VOIP if I switch out the connectors to RJ45?
A: Although the bandwidth with on Category 3 cable is sufficient to use for VOIP it is never recommended. Most problems with VOIP are caused by cabling/network issues. Category 3 is rated at 10mbps and in order to attempt to use it for VOIP all connecting switches must be programmed to run at that limited throughput. You cannot set the switches to auto-negotiate, they must be programmed and, in addition all must be set to full duplex. Full duplex does not play well at 10mbps.
Even doing everything correctly does not guarantee a quality VOIP call. I would strongly recommend a minimum of Cat5e or Cat 6 cabling for all VOIP installations.