VoIP and 911: Is Your Agency Prepared?


Ever since the public was first made aware of the Internet, people and companies have been creating applications and systems to make our lives easier and make our spending more efficient. One of these systems is the adaptation of a technology called “Voice over Internet Protocol,” or “VoIP,” which allows voice to be transmitted over the Internet as a digital signal hidden in the network traffic rather than as a true electrical signal.

The telephone companies have been using VoIP for years to connect their central offices, where the telephone lines from individual businesses and residences converge and are interconnected to other central offices or to a long-distance carrier. A switchboard operator used to manually “patch” the calls by plugging a cable from the subscriber into another plug for another subscriber or for a long-distance call. Electronic switches have since replaced the switchboard operator.

These network lines use a data transmission method called “Internet Protocol” (IP), one of several ways data can be sent across a network. Web browsers and other Internet-capable computer programs also use IP to connect to servers throughout the Internet.

In the past few years, simple “chat” programs, through which one computer user can send messages to another across the Internet, have expanded to include voice and video transmissions. The voice part of these chat programs uses VoIP technology to bring the voice across the Internet. This technology was then further advanced to allow VoIP devices to connect to the public switched telephone network (photo 1). Companies such as Vonage began making this available to the general public as an alternative to a traditional telephone system, sometimes referred to as POTS (“plain old telephone service”). Currently, there are more than 100 VoIP providers in the United States (Figure 1).

(1) A nonproprietary VoIP adapter made by Motorola for Vonage VoIP service. (Photo by author.)


Figure 1. How Voice over Internet Protocol (VoIP) Works



Some advantages of subscribing to a VoIP service instead of a POTS service include the following:

  • A substantial cost savings to the customer. Since all of the calls are transmitted over the Internet, long-distance phone calls are usually included in the pricing. The overall pricing for VoIP providers is usually significantly lower than that for POTS providers.
  • Most VoIP providers allow you to have a phone number in another calling area or area code that rings at the subscriber’s location as if it were the local number that was being called.
  • A computer can be interfaced into the system to allow for greater flexibility.
  • The VoIP device can be plugged into any Internet connection, allowing you to bring your phone service with you when on trips or relocating.

These advantages are what prompt many people to abandon their traditional telephone service and subscribe with a VoIP provider. Unfortunately, the technology that provides these advantages also creates some very significant disadvantages, mostly involving emergency calling:

  • When the Internet connection is down, the telephone service is not available.
  • During a power loss, the VoIP device (and, in some cases, the telephone) is not available.
  • For those using a cable Internet connection, during a power loss, the digital signal across the cable is usually lost, which also makes the telephone service unavailable.
  • If the subscriber’s address on file with the VoIP provider is in an area where the local public safety answering point (PSAP) does not have a VoIP/Enhanced 911 (E-911) connection, then an emergency services operator provided by the VoIP provider answers the 911 calls. This operator then transfers the call to the business line of the appropriate PSAP to dispatch the emergency services. This is prone to error since the wrong PSAP may be notified, delaying emergency services response.
  • The VoIP provider may have the wrong telephone numbers on file for the local PSAP if the subscriber’s 911 call is not automatically routed to the appropriate PSAP.
  • If the subscriber has moved his VoIP equipment to a location other than that which is on file with the VoIP provider, the emergency call may be routed to the wrong PSAP with the wrong address information.

Note that the problems described above impact 911 service. There are a whole set of additional problems when considering the VoIP impact on the transmission of fire alarm system signals. Those issues are not considered in this article.

In traditional E-911 systems, when a 911 call is placed, the local telephone service’s computer equipment routes the call to the PSAP designated to handle emergency calls from the subscriber’s location. The subscriber’s address is obtained from the telephone service’s E-911 address database, transmitted via a dedicated line to the PSAP, and is displayed on the E-911 equipment at the PSAP as well as imported into the computer-aided dispatch system, if one is used.

With VoIP E-911 calling, if the PSAP is equipped to handle the transfer of data from the VoIP provider, the information is basically sent the same way as traditional E-911. In most cases, this works fine. However, there are many cases where this will not work. Public safety agency administrators should be aware of some potential difficulties a caller may have when calling 911 from a VoIP provider and should have some policies in place to deal with these difficulties when the call is routed to their administration lines instead of to the PSAP.

Before 2005, most VoIP providers provided limited or no E-911 dialing support. In May 2005, the Federal Communications Commission (FCC) issued order FCC 05-116, which mandated VoIP providers to provide E-911 services to their subscribers. They were ordered to stop taking new customers in areas in which the VoIP did not have E-911 service, and a target date of November 28, 2005, was set for all VoIP services to comply. For the most part, the VoIP services met this requirement by the target date, but some existing customers still could not be connected directly to the local PSAP when dialing 911. To date, most of the customers can be connected to the local PSAP; but if the customer moves to an area where E-911 service is not provided or available, the problems can still occur.

It is impractical to contact every VoIP provider to make sure it has the correct numbers for your PSAP, even though this would be the best option. Instead, make sure all operators are aware that there is a chance they may receive an emergency call on their business line, especially if they are located at the public safety agency’s administrative offices and not inside of the PSAP. Have a policy or procedure in place for handling these types of calls.

An agency should ensure the following are included in any policy or procedure developed to deal with emergency calls that are received at a non-PSAP location:

  • Public safety agency operators and receptionists, especially those located physically outside of the PSAP, should have a procedure to follow when an emergency call is received. Never include instructions like “Tell the caller to hang up and call 911” as part of this procedure.
  • Ideally, a mechanism should be in place to allow for one-touch transfer of calls received on nonemergency lines within the agency to the PSAP.
  • These procedures should have the correct phone numbers if a one-touch transfer mechanism is not possible. The caller should then be forwarded to the appropriate number.
  • As part of the procedure, the person initially answering the emergency call should obtain, at a minimum, the location of the call, the nature of the call, and a callback number before transferring the call.


I have some personal experience with this type of problem. I had a medical emergency at my residence that necessitated that I dial 911. At the time, I was a subscriber with a now-defunct VoIP provider that did not have my calling area connected to the local PSAP. So, my 911 call was routed to the VoIP provider’s emergency services operator. She took my information and transferred me to the number that she had as the “business line” of the local PSAP.

Unfortunately, the call was not forwarded to the business line for the PSAP but to the business line for the local police department. The police department switchboard operator is not located in the PSAP but in the police headquarters building about a mile away. The PSAP is run by the sheriff’s office, but it has dispatchers for all emergency response agencies in the county, including the county EMS and city police and fire departments. Since the sheriff runs the PSAP, the police department operator then transferred me to the sheriff’s office business line.

I told them I had a medical emergency, and they attempted to transfer me to a county EMS dispatcher, but the call was then disconnected. I was on the phone for about three or four minutes total, and no units were ever dispatched to my address during this call. With all of these transfers, no one but the VoIP operator ever asked me for my address or a callback number.

Instead of retrying the call from my VoIP phone, I decided to call from my cell phone. The call was answered by a 911 call taker in the local PSAP. That call taker then successfully transferred me to a county EMS call taker, who then took my information, and the appropriate units were dispatched. This time, I was on the phone for about 25 seconds before units were dispatched to my residence.

Fortunately, everything worked out, and everyone is fine, but it made me aware of the problems presented by calling 911 over a VoIP phone. If the police department and sheriff’s office had the appropriate procedures in place to ensure calls like mine were handled appropriately, help would have been sent on the first 911 call instead of the second. This may have meant the difference between life and death; fortunately in my case, it did not.


Most 911 calls, whether placed through a VoIP phone line or a traditional phone line, go through without a problem. However, the technology that allows VoIP to provide service creates the potential for significant problems to occur when 911 calls are placed over a VoIP line. Ensuring that there are policies and procedures in place to handle these problems from a public safety agency’s point of view can help to make sure that these calls are handled as expediently as possible.


Federal Communications Commission (FCC), VoIP and 911 Services Web site, www.voip911.gov.

FCC, VoIP and 911 Services Web site, “VoIP Provider Information,” www.voip911.gov/VoipProviders.html.

FCC Order 05-116, May 19, 2005, www.fcc.gov/cgb/voip911order.pdf.

Vonage 911 dialing page Web site, www.vonage.com/features.php?feature=911

CRAIG PRUSANSKY, EMT-P, is a captain/paramedic with and 17-year veteran of Palm Beach County (FL) Fire-Rescue. He served as the department’s systems analyst from 1998 to 2001. He is also the CERT team liaison officer for Palm Beach County Battalion 7 in the western “Glades” communities.

No posts to display