VoIP Phone Buying Guide
There are a plethora of IP phones available which can make selecting the right
phone for your business a difficult task. With several manufacturers each having
multiple models to choose from how do you make the right selection? This
selection guide should help give you all of the information you need to select
an appropriate IP phone for your particular situation.
The information in this selection guide is designed to help you choose an IP
phone to work with the most common open source IP PBX systems such as trixbox,
SwitchVOX, Elastix, AsteriskNow, Asterisk, etc although the concepts will apply
to other legacy PBX systems from Cisco, Avaya, or Nortel. Often you will see
either IP Phone or VoIP phone, both of these terms mean the same thing so don't
be confused by the different terms.
How do I select the right VoIP phone manufacturer?
While traditional PBX systems like Avaya, Nortel, ROLM, and others require their
own brand and even specific models of phones, Open Communication systems and the
open source PBX platforms that we prefer here at Voiplink allow you to select
any compatible phone from any manufacturer. While this gives you a lot more
options, it does give you a lot options to choose from. For most people,
choosing the right phone comes down to features, comfort, and price,
What is SIP, MGCP and SCCP?
Different phone systems communicate with devices using different communication
methods, these communication methods are referred to as protocol. Your IP PBX
system and IP phone have to use the same protocol in order to work together.
Most IP PBX systems, especially open source PBX systems like Asterisk and
Asterisk-based systems like
trixbox, SwitchVox, and AsteriskNOW,
use the SIP protocol as it is an industry standard. MGCP is an older protocol
that some hosted systems still use, but it is being phased out for the more
popular SIP protocol. SCCP (aka Skinny) is Cisco's proprietary VoIP
communication protocol. Ninety-nine percent of all Cisco IP phones ship with
SCCP loaded by default. If you want to use a Cisco phone with an Open
Communication system, it will need to be converted to SIP.
Different phone features
Multiple Call Appearances
IP phones with a single call appearance can still take multiple calls, but are
harder to use to switch between calls. An IP phone with multiple call
appearances (lines) makes it much easier to manage multiple calls and enables
you to use features like three-way conferencing, attended transfers, and BLF
functions (being able to see the status of another extension.
Single line IP phones like the Linksys
Linksys SPA901 are great in situations where there is
very low call volume, like in the back of the warehouse, while a sales manager
may need a six line phone such as a
Polycom 601 to use multiple lines appearances as well
as monitor key employee's extensions. Most people are just fine with phones that
fall in between, such as three line phones such as the Cisco 7940G, Polycom 501,
and Aastra 57i.
Dual Ethernet ports
An IP Phone connects to the IP PBX system over an Ethernet data network, just
like your computers, and often is the same network that your computers uses.
Phones with two Ethernet ports act like a small hub so that you can plug the
phone into the data network and then plug your computer into the phone, thus
only needing a single Ethernet jack in the wall. If your office is prewired and
only has one outlet per office or cubicle, it could be cost-prohibitive to
re-wire the office for two Ethernet jacks, in this case a phone with dual
Ethernet ports can save you a lot of money, if you purchased IP phones with only
a single port, you would then have to put additional switches around the office,
or in some cases in every office or cubicle would would dramatically impact the
cost of the installation.
IP phones require power in order to operate, this can be in the form of an AC
adapter or by using Power over Ethernet. Power over Ethernet (PoE) is a means of
sending power to the phone over the Ethernet, this requires special
PoE switches that the phones connect to and not all phones support PoE. When
ordering a phone, you will need to know if you are going to use PoE or not. If
you are not going to use PoE to power your phones, you will need to make sure
that either the phone you are ordering comes with an included AC adapter of if
you will need to purchase one separately as not every phone comes with an AC
adapter by default. Depending on the phone, the power adapter can run anywhere
from $10 to as much as $40 which can make it more cost effective to use PoE
switches than buying power adapters for each phone. For example, if you are
using the Cisco 7941G, the power supply (CP-PWR-CUBE-3)
will cost you $40.00 per phone. If you deploy 20 phones you would spend $800.00
in power supplies. The
Linksys SRW224P 24 port PoE switch costs around
$450.00, saving you $350.00 in installation cost & decreasing cable clutter and
installation time as well. On smaller installations and phone with cheaper power
supplies, PoE solutions may not be as cost effective.
Some manufacturers such as Polycom, Aastra, and Cisco do not supply power
adapters with every phone so if you are ordering a phone you will need to know
if you need a power supply or not.
All PoE is not created equal
While most modern devices use the industry standard 802.3.af, there are some
older Cisco devices like wireless access points and phones such as the 7912G,
7940G, and 7960G use the proprietary Cisco power over Ethernet implementation.
Newer Cisco phones such as the 7941,7942,7945,7961,7962,7965, and the 797x
series all use the 802.3af PoE implementation. Almost all other manufacturers
including Polycom, Aastra, Linksys, Grandstream and Snom all went with the
802.3af standard which allows them to support a variety of manufacturers' PoE
There are adapters available or you can even create custom cables in order to
provide some compatibility but this is not recommended on production networks.
To begin making your selection of the right IP Phone for your installation,
start with narrowing down the selection based on the protocols (SIP, MGCP, or
SCCP) that your IP PBX system will support and keep in mind that some phones
like Cisco phone may be available in SIP or SCCP but it can be challenging to
switch the firmware from one to the other if you order the phone for the wrong
Second you need to decide on the features that are important to you. Do you need
multiple call appearances, cheaper warehouse phones, nicer executive phones,
phones with sidecars for receptionists, XML application services, or other
features that you will need? Receptionists, managers, and executives may need
phones with multiple call appearances to be able to manage calls easier or
initiate conference calls.
Next you need to consider the network options. Do you want a second network to
separate the phones from your computer network, if so you will need more jacks
and more network switching equipment. If you want to use your existing network
and jacks you will need IP phones with dual Ethernet ports.
Finally, decide if you are going to use Power over Ethernet, if your network
already supports it or if you decide to use PoE you can save on cable clutter,
and in some cases even save money depending on the type and quantity of phones
you decide to use.
This should have helped you to make a more informed decision regarding your IP
Phone purchase by helping you to understand the differences between the
different options that are available.