Ensuring that emergency numbers can be reached

A major advantage of Voice over IP is that the connection can be used worldwide, regardless of the connection address. However, this can lead to problems with emergency calls, because

• the transmitted telephone number determines which emergency call centre is responsible.
• If no location details can be provided during an emergency call (e.g. a ‘gasping for breath’ call), the connection address associated with the phone number is determined. Emergency services will then be dispatched to this address.

However, to ensure that the correct address can be identified in an emergency, you should only make emergency calls from a line registered to the address where you are currently located. 

• If you are working remotely, please use your mobile number to make an emergency call.
• If you are working from home, please use your private landline or your mobile number for emergency calls, rather than your office number.

Individual number signalling does not affect which emergency call centre is contacted. We contact the emergency call centre associated with the address linked to the customer’s account number and pass on the correct phone number for the SIP account.

In many telephone systems, emergency numbers can be defined so that they are handled separately. Some or even all of the points in this article will then be implemented automatically.

If in doubt, you should check with the manufacturer to find out whether, and to what extent, your telephone system supports this function.

For the call to go through, both parties must agree on a codec. In the case of Voice over IP, it has been agreed that emergency call centres must accept the G.711A codec (see Framework for Emergency Calling Using Internet Multimedia).

Please therefore ensure that G.711A is correctly configured and available in your telephone system.

Most telephone systems on the market first check for internal numbers or speed dials when routing calls. Only then is the call routed externally to the relevant provider.

If emergency numbers such as 112, 117, 118 or 144 were assigned as internal speed dials, all emergency calls would be intercepted internally and would not reach the emergency call centre.

Telephone systems often modify phone numbers before passing them on to the service provider. A common example of this is when the country code and area code are automatically added to the start of a number if they have not been dialled.

It is therefore essential to ensure that the emergency numbers 112, 117, 118, 144 and 1414 are always transmitted directly and unchanged. This is automatically ensured in Easybell’s Cloud PBX.