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Small Telephone Systems vs. Multi-Line Business Phones Print E-mail
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Small Telephone Systems vs. Multi-Line Business Phones

By: Damian Parkins. Wednesday, August 5th 2009 17:30pm

Choosing the right telephone system from start is always the best path, but not always the most economical. Before you head down to your local electronic store and pick up the cheapest multi-line business phone you can find, here are few pointers you should keep in mind.

Many multi-line business phones have a pretty decent feature set such as voicemail, caller ID, call waiting ID, 3 way calling and intercom (in multi phone setups). These phones integrate the Key System Unit (or KSU) into the phone itself, which means each individual telephone functions as its own “mini phone system.” KSU: (Key System Unit, Key Signaling Unit or Key Service Unit) is a term which dates back to the early day’s phone systems. It’s basically “the Brain” of the phone system. All call processing functions and telephone line interfacing / signaling is carried out by the KSU. For many small offices with less than 4 phones (extensions) and 4 telephone lines, these multi-line phones are adequate and economical. However, as a business grows, the many disadvantages of these phones begin to show their merits.

By comparison, multi-line business phones are sold with the marketing term, “KSU-less design,” which translates (in buyers minds) to lower overall costs. Small telephone systems on the other hand include a separate KSU unit or “Brain” in addition to each telephone. A major disadvantage comes to play when you are interfacing your phones with the telephone company lines. The KSU acts as the “line interface,” for a phone system, all major system connections terminate at the KSU. Now with each mutli line phone acting as its own “mini phone system,” each phone now needs direct connections to each telephone line.

A single telephone line consists of 1 pair of wires. Almost all multi-line phones support 4 lines maximum, meaning each multi-line phone needs up to 4 pairs of wires (or a standard Cat5e cable). As you begin to add more KSU-less phones to your office you must factor in the cost to install another drop of cat5e (or cat5) cable. You must also account for the additional termination blocks in your telephone closet where all these phones must be “Bridged” (or shared) to the 4 phone lines. As you can imagine for installations with more than say 4 or 5 phones, the wiring aspect can get pretty complex. Anything over 6 or 7 phones will be a wiring mess, if done unprofessionally, which adds to the cost of these low budget systems. However, this bridged connection is how multi-line phones effectively “intercom” one another. By sending a signal over each bridged line, each extension can communicate internally without tying up any of the 4 phone lines. As long as every multi–line phone is connected to all 4 lines (or matching number of lines if less than 4), each phone can intercom to each other internally while keeping the phone lines free for external calls.


Small Telephones Systems on the other hand, which come equipped with a separate, dedicated KSU unit, are at a distinct advantage in both areas. Having a single KSU unit means a single interface point for the telephone line connections. Many small business telephone systems need only a single pair of wire to connect each extension telephone. What this means is if you are deploying a number of phones in one particular area, you can save dramatically on cabling costs by having your contractor “split” the single Cat5e cable into, at most, 4 single telephone jacks! – This becomes very cost effective as you deploy additional phones. (However, many pro’s only split single Cat5 cable once for 2 telephone jacks leaving the remaining wires as spare pairs). Cable management becomes much easier (and neater) as you need not worry about bridging 10 phones to 4 telephone lines. One single pair of wires (to connect to the telephone) of the 3 or 4 pairs in a standard telephone cable is enough for as many lines as the small telephone system can handle since the actual line connections are at the dedicated KSU and not the telephone.

Another plus for the small telephone system is the ease of transitioning to a larger phone system. The wiring scheme for the most part will remain the same albeit installing more cable drops to new areas. Not so much the same for the multi-line business phones. Depending on how each phone was “bridged” to interface to those 4 telephone lines, this entire wiring scheme may need to be undone as most small (and large) telephone systems require individual (not bridged or shared) connections to the KSU.


Programming wise there is one disadvantage when comparing small business telephone systems to multi-line business phones, which can be viewed as multiple disadvantages. Since each individual telephone functions as its own KSU it also functions as its own Voicemail unit (if equipped). Which means if you want to enable an Auto Attendant feature (where your callers are greeted by a company recording instructing them to press 1 for Joe Boss, 2 for Sales Manager etc…) you will have to record this greeting for as many times as you have voicemail enabled phones (up to 4). Here’s why, with most multi-line business phones, the voicemail feature includes a personal voicemail box for the extension and an optional auto attendant feature. The auto attendant feature can only handle one call at a time; ergo if you want the system to answer up to 4 incoming calls simultaneously you need at least 4 auto attendant enabled phones. So technically speaking you must record the same auto attendant greeting 4 times, 1 on each phone. You must also enable the system mailbox for each of the 4 phones to accept general messages. You now have 4 different phones/voicemail boxes in your office where you must check for general messages. General Mailbox: A destination in a voice mail system where callers are routed if they do not press a menu option or dial an extension. This scenario is not efficient for larger setups but may work for smaller ones.

With a small business telephone system, there is just one central voicemail unit which can handle multiple calls at once. Storage times are much greater and there is just one mailbox for general messages. You can also take advantage of advanced features (if equipped) such as voicemail to email (where the systems sends the voicemail in a standard .wav format to your email address), which in this fast paced world can be a BIG time saver and added convenience.

One last point on this topic I'd like to cover; with the advent of the Voice over Internet Protocol (VoIP) continually proving its cost effective existence, many businesses find themselves wanting to take advantage of these savings. Many small telephone systems on the market are equipped to handle VoIP telephone lines through either a simple hardware or software upgrade. An upgrade may include adding an Ethernet port to the system, or enabling an existing port through a software activation. Simply plugging this unit into your company LAN and perhaps performing minor firewall configuration you can now start saving on land line costs by calling out over less expensive VoIP lines.

Multi-line business telephone can benefit as well via through a 3rd party VoIP gateway. This gateway converts a VoIP line (sometimes called a "Trunk") to a standard telephone port. You will need as many gateways as you want lines, (or opt for a multi-port unit). However you may have to plan on spending some time configuring and adjusting the settings of the unit to obtain the proper volume levels while minimizing echo and other artifacts that may be induced when converting the signal from a standard Analog telephone line to SIP or other VoIP protocol. Many high end units come with built in (hardware or software) echo cancellers and noise suppressors which minimize these adjustments (and work very well) but increase the cost of the gateway dramatically.


To conclude,although it may seem like great savings early in your start up phase, for needs of 4 or less external lines and extension phones, the multi-line business phone can actually prove to be a cost effective solution. In my humble opinion, these multi-line phones are better suited for a home office (or SOHO) situation. If you have big plans to expand exponentially (and don’t we all!) I recommend you at least consider a small business telephone system. Although a bit more initial investment is required, the benefits far out way the cost disadvantage if not cancel it out completely.



If you’re looking for a great small telephone system to start out with that’s not too advanced and bloated with “bells and whistles,” I recommend the XBlue Networks X16 small office telephone system. This system is priced right smack in the middle of a decent multi-line business phone setup and an advanced small business telephone system. XBlue Networks hit the nail on the head with this model by stripping off only the advanced telephone features most small business may not have a need for or are rarely used; allowing the X16 small office phone system to fill a niche in the market left primarily untouched. This compact, stylish phone system offers some nice designer series phones to choose from (for those wishing to be unique) and a great feature set. If you’re local to the New York City metro area, PBX Interactive, LLC currently has a great promotion going on for these small telephone systems. Feel free to give us a call at 718-272-0206 or just click the following link to take advantage a nice starter phone system:

XBlue X16 Small Telephone System - Blowout Sale!


About the author:

Damian Parkins is the Operating Manager / Sr. Telecom Specialist here at PBX Interactive, LLC. He has over 12 years engineering experience in the Telecom industry, with many different system types and telephony platforms under his belt. He has designed many custom telephony solutions for our clients and has interfaced with many leading vendors in the industry. Damian is constantly undergoing training in the latest advancements in telecom technology and is one of our main content providers here at the PBXi™ Web Portal.



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