An E911 emergency number is dialled out from a user who chooses the E911number e.g. "9 "" 1 "" 1" to get a connection to the PUBLIC Safty Answering Point (PSAP). The E911 phone number can also have another numeric string which is provided by administration.

The emergency call number E911 is connected with high priority via ISDN direct to the Central Office. The emergency number has also injected into the setup data about the geographical location of the physical apparatus from where the call was made. This is acheived by means of a code (LIN) with the Calling party's number . This transmitted data are identified by a data base (Ali) (PSAP) and further information given to an operator such as floor or room location.

E911 connection can also be made via a Transit systems (also OpenScape 4000) with CorNet-NQ, CorNet-N and Analog connections All information cannot be transmitted by CorNet N or analog connection. The missing information of CPN, LIN is completed in the next OpenScape 4000 system with the data of its own. The LIN is read from the Circuit and the CPN comes from the system.

In Network connections from the subscriber to the PSAP including transit connections ,EMCYRTT=Y must be set on all E911 Routes. Also on circuits used for E911 a LIN must be administered and in every system a System wide emergency callback number in AMO ZAND configured, this is required to transmit the information about CPN and LIN for E911 calls to the relevant correctly registered PSAP.