Here's a sobering thought: Your teenager can make calls, send text messages, play video games and transmit photos from her cell phone.

But your employees at work can't move to another desk without losing access to their telephone extension, voice mail or calling features.

What's wrong with this picture? Antiquated PBX technology, that's what.

While cell phone services have been moving at warp speed, time has stood still for traditional small-business phone systems. If you're like most companies, you've expanded your business reach tremendously with e-mail and a Web presence, but your voice communications are still limited by an old-fashioned private branch exchange (PBX) system.

The small-business PBX is just a more modern (but scaled down and less feature-rich) version of the big PBXs that were invented in the horse-and-buggy era. That was in the late 1800s, believe it or not. The idea behind this invention was to create a piece of switching "iron" or hardware that would save the cost of connecting each employee's telephone back to the telephone company's central office by a separate line (or trunk).

With a PBX, all internal calls are switched through the central system, which can support many internal connections. Outbound calls are connected over a smaller number of lines from the PBX back to the central office. Over time, PBXs have been optimized to switch calls very efficiently and provide a wide array of calling features, such as hold, park, transfer, and so on. But in more than 100 years, PBXs have never lost their original purpose — or limitation — as location-centric devices.

It's time for you to break free of the old PBX model of voice communications. Internet Protocol telephony (IPT) carries voice and data traffic over the same network — and lets employees enjoy the kind of flexibility and power in business voice communications that e-mail and the Web give them in accessing text, graphics, and business information.

If the lease is up on your PBX, or you're out of capacity and you need to upgrade, here are five reasons why it's time to make the move to IPT:

1. You can save phone costs and employees' time.

With traditional PBXs, calls made between two locations served by different types of phone systems or services have to be made over the public switched telephone network, and that means toll charges. In addition, employees have to dial as many as 12 digits just to reach a co-worker in another office. IPT puts everyone on the same network, saving on telecommunications costs and employees' time.

2. You can offer full service to remote workers.

A PBX makes it difficult and costly to add remote locations. Smaller offices have to be served with less expensive Key systems (a lower-priced, less feature-rich PBX) or telephone company Centrex services. Because headquarters and remote offices don't use the same system, employees end up with different levels or types of voice service.

A teleworker (telecommuter) or one-person sales office is really out on a limb in the PBX world; they have no enhanced voice services at all, except what the local phone company provides in the way of call waiting, caller ID and perhaps three-way calling. IPT makes voice communications as extensible to remote workers and locations as data services are today.

3. You have one network to manage, not two.

Companies must maintain separate networks to handle data and PBX-based voice systems, even when the voice and data traffic are serving the same end-users in the same locations. This is burdensome for small organizations that have to spend money on different staff specialists (or outside vendors) to support their voice and data networks. IPT means one network to manage instead of two.

4. Making changes in the future will be simplified.

Each phone number at a desk is associated with a port on the PBX system. When an employee joins the company or moves to a different cubicle or office, someone has to manually reprogram the PBX to assign a new extension or change voice services (such as assigning the new employee to a call pickup group).

Each move, add, or change is estimated to cost $75-$125 with a traditional PBX. IPT makes it easier and less expensive for employees to move around and take their voice services with them.

5. You can leverage employee mobility.

A PBX system also limits the flexibility in a company with a mobile workforce. When a teleworker or field sales employee comes in to the headquarters office, each is presented with two choices:

• They can continue to use their cell phone, giving up access to the calling features of the office voice system; or

• They can settle into an empty cubicle and then notify all their customers and colleagues of their temporary extension number so that they can use office voice features such as conference calling and call transfer.

IPT associates a user's voice service with the IP phone, not a jack in the wall. That makes it easier for companies to have a mobile workforce, encourage office sharing, and reap other business benefits associated with the technology's flexibility and freedom.