What is a PBX Phone System and how does it compare to a Multi-Line System?

What are multi-line phones?

Multi-line phones are phones that allow you to access more than one phone line without switching phones. The easiest way to explain multi-line phones is to compare them to single line phones. Most of us are familiar with single line phones because that is what we have in our homes. You might have several phones throughout the house, but they are probably all connected to the same phone line. So only one call, either incoming or outgoing, can take place at a time. If you pick up a phone when someone is using another phone in your home, you hear them speaking. You can’t make a call until they hang up. Multi-line phones are used when there is more than one phone line coming into the same home or business. Another option would be to have a different set of phones for each phone line, but that would be hard to manage. Instead, most businesses will use multi-line phones so that each phone has the capability of accessing all the lines coming in. For example, if you had three phone lines coming into your business, you would probably have three-line multi-line phones throughout your office. Each phone would have buttons labeled “LINE 1”, “LINE 2”, and “LINE 3”. If a call came in on line 2, you would push the LINE 2 button and then answer the call. If a second call came in on LINE 3, you could put line 2 on hold, and then press the LINE 3 button to answer the second call. By ordering “roll-over” service from your phone company, you can make a multi-line phone system more efficient. With roll over lines, if someone calls you on line 1 and that line is busy, the phone company will automatically roll the second call to line 2. If both lines are busy, the next incoming call will roll to line 3. That way you only have to publish one phone number, and you can answer multiple calls coming in to that number.

What are the advantages of Multi-Line phones?

The only advantage to multi-line phones over a PBX is that the phones are less expensive than a PBX system.

What are the disadvantages of a multi-line phone system?

Although multi-line phones are made that can handle up to 8 lines, they tend to become ineffective if more than three lines are used, or if call volume is fairly constant. With multi-line phones, call transfers are accident prone and unprofessional. For example, if Dave picks up a call on line 1, and that call is for Sally, Dave will put the caller on hold and yell across the room, “Hey, Sally, pick up line 1”. If Sally is on another line, or away from her desk, then things get more interesting. Dave then has to interrupt his work to take a message, or he has to keep the caller on hold and find Sally. If there are a lot of calls coming in while this is happening, the opportunity for errors increases accordingly. If Dave forgets which line the call is on, Sally is likely to answer the wrong line or the caller can easily be hung-up on. Again, multi-line phones can be very unprofessional and are prone to accidental hang-ups and misdirected calls. Reaching a business with a multi-line phone system sends a clear message to the caller that they have reached a small, somewhat backward, business. The phones are devoid of caller friendly features like professional call answering options, music on hold, dial by name, after hours messages, voice mail options, and clean professional call transfers. Callers who are handled poorly, and especially those who get cut off, are not likely to call back if they have any other option.

What is a PBX Phone System?

The name PBX is a phone company abbreviation for Private Branch Exchange.  The term PBX is used to describe an automated system for handling multiple phone lines. A quality PBX will include voice mail, auto-attendant, and call handling functions like call transfer, call forwarding, dial by name, conference calling and much more. It has caller-friendly features like music on hold, messaging on hold, and after hours messaging. It can be custom programmed to handle virtually any business telephone situation, and the programming can be changed when business needs change. A business with a PBX phone system connects the lines they buy from the phone company to the PBX system. They also connect all the telephones in their office to the PBX, and each phone is assigned an extension number. The PBX then acts as a connection between the phone lines and the telephones. It is pre-programmed and automated. To dial from one phone to another within the office, you just dial the three-digit phone extension number. No outside lines are used for this type of connection, the two extensions are connected inside the PBX. Typically, to get an outside line with a PBX phone system, you pick up any extension and dial 9. The system then finds an available, unused, phone line and connects the extension to it. The caller hears a dial tone and then dials an outside phone number. The caller typically does not even know which phone line he is using, nor does he care. He just knows he is connected to an outside line, which is what he wants. When incoming calls are received by the PBX, it handles those calls according to a set of pre-programmed instructions. Today, most PBX systems are programmed to answer with an auto-attendant. The auto-attendant tells the caller who they have reached (Example: “Thank you for calling the ABC Company.”) Then it gives the caller options on how to reach the party or the department they are calling (Example: “If you know your party’s extension number, you may dial it at any time. For Customer Service press 3, for Sales press 4, to dial by name press 8, or dial 0 for the operator.) The PBX is extremely flexible in how it handles incoming calls. If desired, all incoming calls can be routed through a live operator instead of an auto-attendant. The operator can be one person, or a group of people. Another option is to have an operator answer incoming calls, but if the operator is busy have the calls go to an auto-attendant. However the calls are answered, either by an operator or an auto-attendant, the calls are then routed to a specific extension. When the calls are sent to an extension, either by an operator or by the auto-attendant, there is no need to keep track of the call or the line it came in on. If the extension is busy, or not picked up, the PBX will handle the call in whatever way is desired: the call can be automatically transferred to another extension or to an outside number, or it can be sent to an individual voice mail or to a group voice mail, or it can be returned to an operator or to the auto-attendant, or the caller can be placed on hold by the system while the person they are calling is automatically paged, or many other options. The call is never lost or forgotten. It is always handled according to the way the system is programmed, and no one has to keep track of calls or phone lines.

What are the advantages of a PBX phone system over a multi-line system?

There are several advantages of a PBX phone system:

Increased Efficiency: The PBX system eliminates much or all of the time required to answer and transfer calls as well as the time required to take messages and locate people. It also eliminates much of the wiring required by a multi-line system since only one pair of wires is needed for each phone extension instead of a pair of wires for each phone line to each telephone in the office. 

Flexibility: A good PBX system can be programmed to answer and handle calls just about any way you want. And if your needs change, the same system can be re-programmed to meet your new requirements without having to purchase a new phone system. 

Expandability: A good PBX system is easily expandable. Your system should grow with you without having to replace the whole system and without having to change all your internal procedures for handling calls. 

Professionalism: With a PBX system, your calls are handled in a clean and professional manner. Callers are never hung-up on while being transferred and they are not transferred to the wrong party. Callers are not worried about whether or not their messages are getting through to the intended recipient. Callers are not left on endless holds.

What are the disadvantages of a PBX phone system?

The only disadvantage of a PBX is that it costs more. Until recently, small businesses who needed a PBX system had only one choice: they had to buy a PBX from a dealer and then have it installed by the dealer’s certified technician. Today, small businesses have the option to buy from many smaller VOIP companies that often provide cloud PBX solutions for much cheaper prices.

Can a PBX phone system be set up to function like a multi-line phone system?

Yes, a PBX system can be made to work very much like a multi-line phone system, but the question is why would a business do that? It has been said that programming a PBX to function like a multi-line phone system is like buying a speedboat and then paddling it across the lake. Although the procedures for handling calls are different with a PBX system, once the change is made, everyone is better off. Employees are more productive, the stress level in the office drops, and most importantly, customers are handled more quickly and professionally. (Once you see how well the boat operates with the motor running, you will never go back to paddling.)


Multi-line phone systems work for very small businesses with few phone lines and few calls. When businesses have more than three phone lines, or when their call volume gets higher, they need the efficiency, flexibility, expandability and professional call handling that a PBX system gives them. .

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