Compare PBX T1 PRI and VoIP T1
Services
What's the difference between T1
PRI line service for PBX phone systems and T1 lines that support
VoIP telephony.
Digital business telephone systems can
be based on one of two important technology standards. These
are TDM or Time Division Multiplexing vs VoIP or Voice over Internet
Protocol. Both are digital standards, as opposed to the analog
single line or Key telephone systems found in very small phone
systems. Generally, TDM is associated with PBX or Private Branch
Exchange systems traditionally found in medium and larger size
businesses. VoIP is the newer technology thought to need completely
different equipment and more likely chosen for brand new installations.
But there is more of an overlap in these technologies than you
might think.
Traditional PBX Phone Systems
Legacy PBX phone systems are often designed with very specialized
hardware and programming chosen for high reliability. The phone
sets may be either analog or digital and are individually connected
to the PBX system on their own wiring network. The advantage
of having a PBX system is that it is your own little phone company
within the company. Users can call each other using just 3 or
4 digits and there are no line or per minute charges. It's only
when someone makes a call outside the company that you incur
local or long distance charges. Those outside calls are made
using a group of shared phone lines on a first come, first served
basis.
How T1 PRI Service Fits In
The outside phone lines are most often supplied to the PBX system
using a T1 PRI digital line service. T1 PRI bundles up to 23
local or long distance lines together into one digital line service.
There are actually 24 channels, with one reserved for signaling
and data such as Caller ID. PRI is also known as primary rate
interface. What's important about T1 PRI is that all of the channels
are completely separate just like analog phone lines. If a channel
isn't being used, it just sits there idling until needed. This
channelization prevents crosstalk of one call into another and
degradation of voice quality or dropped calls from signal interference.
T1 PRI is the highest call quality you can get by virtue of it's
strict design characteristics.
Moving Into Network Convergence
If T1 PRI is the gold standard, then why have anything else?
The reason is cost savings. Remember that unused T1 PRI channels
do nothing although you are paying for the entire line by the
month. The other cost that might be saved is having a separate
telephone network with its own wiring plus an incompatible computer
network. Combining the two networks is called convergence. The
slower speed telephone network is converted to a format compatible
with the higher speed computer network so all of the signals
can travel together on one set of wired. That format is called
Ethernet or IP for Internet Protocol. As you might guess, IP
is also the standard used on the actual Internet.
VoIP Telephony
A phone system designed to run on an IP network is called VoIP
for Voice over IP. Instead of having separate phone lines or
channels, the digitized voice is loaded into the same type of
data packets used for transmitting computer data. In a sense,
VoIP packets are computer data as far as IP networks are concerned.
It is up to the network operator, usually the company's IT department,
to ensure that both voice and data have the bandwidth needed
to maintain quality of service.
The conversion from regular telephone signals
to VoIP can be made by an IP PBX system or can be done right
inside the phone set, often called an IP phone or SIP phone.
SIP is a particular protocol used by many but not all IP PBX
systems.
PBX and IP PBX Systems
Notice that in a VoIP phone system the PBX has become an IP PBX.
Some systems use other terminology such as voice gateway or soft
switch. When VoIP calls connect to standard telephones, those
called need to be terminated to the PSTN or Public Switched Telephone
Network. The termination can be analog phone lines or even T1
PRI digital phone lines connected to electronic interface cards
that plug into the IP PBX. Two IP PBX systems are connected together
using an unchannelized T1 line.
Just to mix things up a little further,
legacy PBX systems can also be converged onto computer networks
by adding a IP conversion card to the PBX system. The resulting
IP datastream can be conveyed on a unchannelized T1 line across
long distances or connected to a LAN router or switch. Again,
once converted from TDM to IP format, voice quality is no longer
automatic but must be engineering into the local or wide area
network.
Let our Consultants & VAR Partners
Be of Service
As you can see, there is quite a bit of mix and match possible
when creating a new business telephone system or upgrading a
legacy system. If you have a project in mind be sure to get recommendations
and competitive quotes through our telecommunications
VAR Network.
If
you already have your system, find out how to save on T1 and
PRI telephone service costs now. Simply
fill out the form below to see instant pricing on most services.
Or call toll free 1-866-436-7868
Ref. # 1265 to talk to our technical
consultants about your business needs and receive customized
proposals.
