11.13  
IP Mobility Extension (Emergency) 
 

Definition  
In an IP network, a mobile station can log on either at home or at any other remote network node. In the case of an emergency call from a HFA-IP telephone (HFA: HiPath Feature Access) that is registered at a remote network node, the emergency destination of the remote network node cannot be called. Instead, the emergency destination of the HiPath node where the telephone is connected is called.
The emergency number for the IP phone must be the PABX number of the network node where the phone is connected and that is used for exchange breakout (gateway). If an emergency number is dialed, the resulting call is routed to the HiPath node where the phone is connected (irrespective of the current logical assignment to a remote network node) and routed from there into the exchange.
A direct call to an emergency destination in the public network is not possible because telecom providers do not support this type of access.  
An emergency prefix must be stored in the HFA-IP telephone. This number can be used to reach the emergency destination from anywhere within the network. Emergency numbers for police or fire services (112 or 110 in Germany, for instance) are dialed with a prefix by the subscriber.
It is important that the emergency numbers are configured both in the home system and in the destination system. In the case of varying emergency numbers in different countries (e.g. the emergency number 911 is valid in the US, while 112 must be dialed in Germany), the emergency number of the country in question must also be configured in the system in the destination country.  
To guarantee global availability, the PABX number of the home network node must be stored in the HFA-IP phone together with the international and national station number prefix. This number can be used to reach the emergency destination from anywhere within the network. Emergency numbers for police or fire services (112 or 110 in Germany, for instance) are dialed with a prefix by the subscriber. Emergency numbers must be identified in the LCR dial plan (CDB) for the entire system network to ensure appropriate call routing.
Example of a CDB for a system in Erlangen (09131 80) with partner systems in Munich, Witten, and Boca Raton (U.S.):

Dial plan  

 Digits  
 Route table  
 Attribute  
   
-110  
 11  
 Emerg=yes  
 Dial emergency no. without trunk access code  
-112 ...  
 11  
 yes  
 Dial emergency no. without trunk access code  
0-110  
 11  
 yes  
 Dial emergency no. with trunk access code  
0-112 ...  
 11  
 yes  
 Dial emergency no. with trunk access code  
-911  
 XX  
 yes  
 Example: emergency number for
Boca Raton  
0-0049-89-722-11X  
 12  
 yes  
   
0-0049-2302-667-11X  
 13  
 yes  
   
0-001-561-923-911  
 14  
 yes  
   
Route table XX (for Boca Raton) must be blank to prevent direct dialing.
911 is an emergency number in the U.S.
911 must also be configured as the emergency number in Erlangen.
The emergency number (112) must not be included in the access code.
During logon, the stored emergency destination number is transferred from the IP telephone to the system. If configured, the Location Identification Number (LIN) in the U.S. must also be transferred to the system once the telephone has logged on. Just like the LIN, the emergency number is also part of the non-mobile station profile. This function is already supported by the telephones and clients.
When a subscriber dials the emergency number, the algorithm checks whether or not an emergency number has been configured on the telephone. This number can then be added to the digits dialed by the subscriber. Otherwise, the digits dialed by the subscriber are evaluated as normal. This algorithm allows for more than one emergency number (e.g. 112 and 110). Consequently, only the prefix for the emergency number is stored (e.g. 49 89 722).
Every number identified as an emergency number in the dial plan refers to an entry in the route table. Every entry in the route table that is associated with an emergency number must be assigned a "low" class of service (COS). "Low" means that all stations are assigned the appropriate class of service. Stations should never be prevented from making emergency calls due to insufficient classes of service.
In other words, every station must be able to dial the short emergency number and signal an emergency by dialing the long emergency number, irrespective of its classes of service.
It is important that the emergency numbers are configured both in the home system and in the destination system. In the case of varying emergency numbers in different countries (e.g. the emergency number 911 is valid in the US, while 112 must be dialed in Germany), the emergency number of the country in question must also be configured in the system in the destination country.  

Model-Specific Data  

 Subject  
 HiPath 3800  
 HiPath 3550  
 HiPath 3500  
 HiPath 3350  
 HiPath 3300  
Feature available in  
 x  
 x  
 x  
Hardware requirements  
 IP workpoint clients  
Software requirements  
 V6.0 or later  
 V6.0 or later  
 V6.0 or later  

HiPath 3000/5000 V9, Feature Description, Issue 7   up Top
Disclaimer & Copyright   ID: P31003H3590F100017618   2012-06-25