Allow sending "Emergency Number List IE" in LU ACCEPT
TS 24.008 allows a list of emergency numbers sent alongside with the LU ACCEPT. Specifically see Section 126.96.36.199:
The network may also send a list of local emergency numbers in the LOCATION UPDATING ACCEPT, by including the Emergency Number List IE. The mobile equipment shall store the list, as provided by the network, except that any emergency number that is already stored in the SIM/USIM shall be removed from the list before it is stored by the mobile equipment. If there are no emergency numbers stored on the SIM/USIM, then before storing the received list the mobile equipment shall remove from it any emergency number stored permanently in the ME for use in this case (see 3GPP TS 22.101 ). The list stored in the mobile equipment shall be replaced on each receipt of a new Emergency Number List IE. The emergency number(s) received in the Emergency Number List IE are valid only in networks with the same MCC as in the cell on which this IE is received. If no list is contained in the LOCATION UPDATING ACCEPT message, then the stored list in the mobile equipment shall be kept, except if the mobile equipment has successfully registered to a PLMN with an MCC different from that of the last registered PLMN. The mobile equipment shall use the stored list of emergency numbers received from the network in addition to the emergency numbers stored on the SIM/USIM or ME to detect that the number dialled is an emergency number. NOTE 2: The mobile equipment may use the emergency numbers list to assist the end user in determining whether the dialled number is intended for an emergency service or for another destination, e.g. a local directory service. The possible interactions with the end user are implementation specific. The list of emergency numbers shall be deleted at switch off and removal of the SIM/USIM. The mobile equipment shall be able to store up to ten local emergency numbers received from the network.
As this IE is also permitted by the SGSN, we should have the related encoder function in libosmogsm so it can be shared between MSC and SGSN.
The IE format itself is defined in Section 10.5.3.13