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Emergency Call

 

Everybody would know what Emergency Call is.. (it is like 911 in north america, 112 in South Korea etc). So I would not explain what Emergency call is. I will focus more on the type of conditions in which the emergency call is allowed and the details of emergency call protocol sequence.

 

You can make an Emergency call in several different condition as listed below.

  • i) The Cell is not Barred for Emergency Call
  • ii) UE is registered to a cell
  • iii) UE has a USIM but the USIM is not provisioned by the network in which the UE is in (In this case, UE would not perform the registeration process to the cell)
  • iv) UE does not have any USIM in it(In this case, UE would not perform the registeration process to the cell)

 

Followings are the protocol sequence and message details for typical cases of emergency call in WCDMA.

 

 

Case 1 : Normal Registration and Normal USIM

 

When you have a USIM in the phone, overall Emergency Call processing is very similar to normal call process except a couple of information elements as marked in the following links.

    01) < In Idle Mode >

    02) < Make an Emergency Call from UE >

    03) RACH Preamble

    04) AICH

    05) RACH Message

    06) RRC : RRC Connection Request

    07) RRC : RRC Connection Setup

    08) RRC : RRC Connection Setup Complete

    09) RRC: initialDirectTransfer + MM : CM Service Request

    10) RRC : downlinkDirectTransfer + MM:Authentication Request

    11) RRC : uplinkDirectTransfer + MM:Authentication Response

    12) RRC : Security Mode Command

    13) RRC : Security Mode Complete

    14) RRC : uplinkDirectTransfer + CC : Emergency Setup

    15) RRC : downlinkDirectTransfer + CC : Call Proceeding

    16) RRC : Radio Bearer Setup

    17) RRC : Radio Bearer Setup Complete

    18) RRC : downlinkDirectTransfer + CC : Alerting

    19) RRC : uplinkDirectTransfer + CC : Connect

    20) RRC : downlinkDirectTransfer + CC : Connect Acknowledge

    21) < Voice Traffic >

     

 

< 06) RRC : RRC Connection Request >

 

rrcConnectionRequest

    initialUE-Identity: imsi (0)

        imsi: 15 items

            Item 0

                Digit: 0

            Item 1

                Digit: 0

            Item 2

                Digit: 1

            Item 3

                Digit: 0

            Item 4

                Digit: 1

            Item 5

                Digit: 0

            Item 6

                Digit: 1

            Item 7

                Digit: 2

            Item 8

                Digit: 3

            Item 9

                Digit: 4

            Item 10

                Digit: 5

            Item 11

                Digit: 6

            Item 12

                Digit: 7

            Item 13

                Digit: 8

            Item 14

                Digit: 9

    establishmentCause: emergencyCall (9)

    protocolErrorIndicator: noError (0)

    measuredResultsOnRACH

        currentCell

            modeSpecificInfo: fdd (0)

                fdd

                    measurementQuantity: cpich-Ec-N0 (0)

                        cpich-Ec-N0: 43

    v3d0NonCriticalExtensions

        rRCConnectionRequest-v3d0ext

        v4b0NonCriticalExtensions

            rrcConnectionRequest-v4b0ext

                accessStratumReleaseIndicator: rel-8 (4)

            v590NonCriticalExtensions

                rrcConnectionRequest-v590ext

                    0... .... predefinedConfigStatusInfo: False

                v690NonCriticalExtensions

                    rrcConnectionRequest-v690ext

                        ueCapabilityIndication: hsdch-edch (1)

                        domainIndicator: cs-domain (0)

                            cs-domain

                                csCallType: speech (0)

                    v6b0NonCriticalExtensions

                        rrcConnectionRequest-v6b0ext

                        v6e0NonCriticalExtensions

                        rrcConnectionRequest-v6e0ext

                            v770NonCriticalExtensions

                                rrcConnectionRequest-v770ext

                                    mac-ehsSupport: true (0)

                                v7b0NonCriticalExtensions

                                    rrcConnectionRequest-v7b0ext

                                    v860NonCriticalExtensions

                                        rrcConnectionRequest-v860ext

    UL CCCH (Hex) : 38 90 01 01 01 23 45 67 89 48 2B A9 68 A9 40 00 00 00 00 00 00

 

 

< 09) RRC: initialDirectTransfer + MM : CM Service Request >

 

initialDirectTransfer

    cn-DomainIdentity: cs-domain (0)

    intraDomainNasNodeSelector

        version: release99 (0)

            release99

                cn-Type: gsm-Map-IDNNS (0)

                    gsm-Map-IDNNS

                        routingbasis: localPTMSI (0)

                            localPTMSI

                                routingparameter: 0000

                        0... .... dummy: False

    nas-Message: 052402035758a605f400000000

    GSM A-I/F DTAP - CM Service Request

        Protocol Discriminator: Mobility Management messages

            .... 0101 = Protocol discriminator: Mobility Management messages (0x05)

            0000 .... = Skip Indicator: No indication of selected PLMN (0)

        00.. .... = Sequence number: 0

        ..10 0100 = DTAP Mobility Management Message Type: CM Service Request (0x24)

        Ciphering Key Sequence Number

            0... .... = Spare bit(s): 0

            .000 .... = Ciphering Key Sequence Number: 0

        CM Service Type

            .... 0010 = Service Type: (2) Emergency call establishment

        Mobile Station Classmark 2

            Length: 3

            0... .... = Spare: 0

            .10. .... = Revision Level: Used by mobile stations supporting R99

                        or later versions of the protocol (2)

            ...1 .... = ES IND: Controlled Early Classmark Sending option is implemented in the MS

            .... 0... = A5/1 algorithm supported: encryption algorithm A5/1 available

            .... .111 = RF Power Capability: RF Power capability is irrelevant in this information element (7)

            0... .... = Spare: 0

            .1.. .... = PS capability (pseudo-synchronization capability): PS capability present

            ..01 .... = SS Screening Indicator: Capability of handling of ellipsis notation

                        and phase 2 error handling  (1)

            .... 1... = SM capability (MT SMS pt to pt capability):

                        Mobile station supports mobile terminated point to point SMS

            .... .0.. = VBS notification reception: no VBS capability or no notifications wanted

            .... ..0. = VGCS notification reception: no VGCS capability or no notifications wanted

            .... ...0 = FC Frequency Capability: The MS does not support the E-GSM or R-GSM band

            1... .... = CM3: The MS supports options that are indicated in classmark 3 IE

            .0.. .... = Spare: 0

            ..1. .... = LCS VA capability (LCS value added location request notification capability):

                        LCS value added location request notification capability supported

            ...0 .... = UCS2 treatment: the ME has a preference for the default alphabet

            .... 0... = SoLSA: The ME does not support SoLSA

            .... .1.. = CMSP: CM Service Prompt:

                        Network initiated MO CM connection request supported for at least one CM protocol

            .... ..1. = A5/3 algorithm supported: encryption algorithm A5/3 available

            .... ...0 = A5/2 algorithm supported: encryption algorithm A5/2 not available

        Mobile Identity - TMSI/P-TMSI (0x0000)

            Length: 5

            1111 .... = Unused: 0x0f

            .... 0... = Odd/even indication: Even number of identity digits

            .... .100 = Mobile Identity Type: TMSI/P-TMSI/M-TMSI (4)

            TMSI/P-TMSI: 0x00000000

    v3a0NonCriticalExtensions

        initialDirectTransfer-v3a0ext

            start-Value: 000040 [bit length 20, 4 LSB pad bits, 0000 0000  0000 0000  0100 .... decimal value 4]

        laterNonCriticalExtensions

            v590NonCriticalExtensions

                initialDirectTransfer-v590ext

                v690NonCriticalExtensions

                    initialDirectTransfer-v690ext

                    v770NonCriticalExtensions

                        initialDirectTransfer-v770ext

                        v860NonCriticalExtensions

                            initialDirectTransfer-v860ext

                                supportOfCSG: true (0)

    UL DCCH (Hex) : 15 00 00 00 60 29 20 10 1A BA C5 30 2F A0 00 00 00 06 00 00 8D 12

 

< 14) RRC : uplinkDirectTransfer + CC : Emergency Setup >

 

uplinkDirectTransfer

    cn-DomainIdentity: cs-domain (0)

    nas-Message: 038e040660040200058140080402600000021f002e0104

    GSM A-I/F DTAP - Emergency Setup

        Protocol Discriminator: Call Control; call related SS messages

            .... 0011 = Protocol discriminator: Call Control; call related SS messages (0x03)

            0... .... = TI flag: allocated by sender

            .000 .... = TIO: 0

        10.. .... = Sequence number: 2

        ..00 1110 = DTAP Call Control Message Type: Emergency Setup (0x0e)

        Bearer Capability - (MS supports at least full rate speech version 1 and half rate speech version 1.

              MS has a greater preference for full rate speech version 1 than for half rate speech version 1)

            Element ID: 0x04

            Length: 6

            Octet 3

            0... .... = Extension: Extended

                .11. .... = Radio channel requirement: MS supports at least full rate speech version 1  

                            and half rate speech version 1.

                            MS has a greater preference for full rate speech version 1

                            than for half rate speech version 1

                ...0 .... = Coding standard: GSM standardized coding

                .... 0... = Transfer mode: circuit

                .... .000 = Information transfer capability: Speech (0x00)

            Octets 3a - Speech Versions

                0... .... = Extension: Extended

                .0.. .... = Coding: octet used for extension of information transfer capability

                ..00 .... = Spare bit(s): 0

                .... 0100 = Speech version indication: GSM full rate speech version 3(FR AMR) (0x04)

                0... .... = Extension: Extended

                .0.. .... = Coding: octet used for extension of information transfer capability

                ..00 .... = Spare bit(s): 0

                .... 0010 = Speech version indication: GSM full rate speech version 2(GSM EFR) (0x02)

                0... .... = Extension: Extended

                .0.. .... = Coding: octet used for extension of information transfer capability

                ..00 .... = Spare bit(s): 0

                .... 0000 = Speech version indication: GSM full rate speech version 1(GSM FR) (0x00)

                0... .... = Extension: Extended

                .0.. .... = Coding: octet used for extension of information transfer capability

                ..00 .... = Spare bit(s): 0

                .... 0101 = Speech version indication: GSM half rate speech version 3(HR AMR) (0x05)

                1... .... = Extension: No Extension

                .0.. .... = Coding: octet used for extension of information transfer capability

                ..00 .... = Spare bit(s): 0

                .... 0001 = Speech version indication: GSM half rate speech version 1(GSM HR) (0x01)

        Supported Codec List

            Element ID: 0x40

            Length: 8

            System Identification (SysID): UMTS (0x04)

            Bitmap Length: 2

            Codec Bitmap for SysID 1

                0... .... = TDMA EFR: False

                .1.. .... = UMTS AMR 2: True

                ..1. .... = UMTS AMR: True

                ...0 .... = HR AMR: False

                .... 0... = FR AMR: False

                .... .0.. = GSM EFR: False

                .... ..0. = GSM HR: False

                .... ...0 = GSM FR: False

                00.. .... = Spare bit(s): 0

                ..0. .... = OHR AMR-WB: False

                ...0 .... = OFR AMR-WB: False

                .... 0... = OHR AMR: False

                .... .0.. = UMTS AMR-WB: False

                .... ..0. = FR AMR-WB: False

                .... ...0 = PDC EFR: False

            System Identification (SysID): GSM (0x00)

            Bitmap Length: 2

            Codec Bitmap for SysID 2

                0... .... = TDMA EFR: False

                .0.. .... = UMTS AMR 2: False

                ..0. .... = UMTS AMR: False

                ...1 .... = HR AMR: True

                .... 1... = FR AMR: True

                .... .1.. = GSM EFR: True

                .... ..1. = GSM HR: True

                .... ...1 = GSM FR: True

                00.. .... = Spare bit(s): 0

                ..0. .... = OHR AMR-WB: False

                ...0 .... = OFR AMR-WB: False

                .... 0... = OHR AMR: False

                .... .0.. = UMTS AMR-WB: False

                .... ..0. = FR AMR-WB: False

                .... ...0 = PDC EFR: False

        Service Category - Emergency category

            Element ID: 0x2e

            Length: 1

            0... .... = Spare bit(s): 0

            .0.. .... = Automatically initiated eCall: False

            ..0. .... = Manually initiated eCall: False

            ...0 .... = Mountain Rescue: False

            .... 0... = Marine Guard: False

            .... .1.. = Fire Brigade: True

            .... ..0. = Ambulance: False

            .... ...0 = Police: False

    UL DCCH (Hex) : 8B ED 0C 6B 8E C0 0B 01 C7 02 03 30 02 01 00 02 C0 A0 04 02 01 30 00 00 01 0F 80 17 00 82 00  

 

 

Case 2 : No Registration and No USIM

 

When there is No USIM in the phone. You may see on the UE display a kind of warning saying "No SIM inserted. Only Emgergency Call is allowed". When you make an emergency call from UE, it would go through following procedure.

UE would send RRC Connection Request with the cause of Emergency Call and with IMEI (Not IMSI nor TMSI) and Network would allow the call setup without going through Authentication and Security procedure.

    01) < No Registered : Emergency Only Mode >

    02) < Make an Emergency Call from UE >

    03) RACH Preamble

    04) AICH

    05) RACH Message

    06) RRC : RRC Connection Request

    07) RRC : RRC Connection Setup

    08) RRC : RRC Connection Setup Complete

    09) RRC: initialDirectTransfer + MM : CM Service Request

    10) RRC : downlinkDirectTransfer + MM : CM Service Accept

    14) RRC : uplinkDirectTransfer + CC : Emergency Setup

    15) RRC : downlinkDirectTransfer + CC : Call Proceeding

    16) RRC : Radio Bearer Setup

    17) RRC : Radio Bearer Setup Complete

    18) RRC : downlinkDirectTransfer + CC : Alerting

    19) RRC : uplinkDirectTransfer + CC : Connect

    20) RRC : downlinkDirectTransfer + CC : Connect Acknowledge

    21) < Voice Traffic >

 

< 06) RRC : RRC Connection Request >

 

rrcConnectionRequest

    initialUE-Identity: imei (3)

        imei: 15 items

            Item 0

                IMEI-Digit: 3

            Item 1

                IMEI-Digit: 5

            Item 2

                IMEI-Digit: 6

            Item 3

                IMEI-Digit: 4

            Item 4

                IMEI-Digit: 3

            Item 5

                IMEI-Digit: 2

            Item 6

                IMEI-Digit: 0

            Item 7

                IMEI-Digit: 5

            Item 8

                IMEI-Digit: 7

            Item 9

                IMEI-Digit: 9

            Item 10

                IMEI-Digit: 3

            Item 11

                IMEI-Digit: 4

            Item 12

                IMEI-Digit: 5

            Item 13

                IMEI-Digit: 3

            Item 14

                IMEI-Digit: 0

    establishmentCause: emergencyCall (9)

    protocolErrorIndicator: noError (0)

    measuredResultsOnRACH

        currentCell

            modeSpecificInfo: fdd (0)

                fdd

                    measurementQuantity: cpich-Ec-N0 (0)

                        cpich-Ec-N0: 43

    v3d0NonCriticalExtensions

        rRCConnectionRequest-v3d0ext

        v4b0NonCriticalExtensions

            rrcConnectionRequest-v4b0ext

                accessStratumReleaseIndicator: rel-8 (4)

            v590NonCriticalExtensions

                rrcConnectionRequest-v590ext

                    .... 0... predefinedConfigStatusInfo: False

                v690NonCriticalExtensions

                    rrcConnectionRequest-v690ext

                        ueCapabilityIndication: hsdch-edch (1)

                        domainIndicator: cs-domain (0)

                            cs-domain

                                csCallType: speech (0)

                    v6b0NonCriticalExtensions

                        rrcConnectionRequest-v6b0ext

                        v6e0NonCriticalExtensions

                            rrcConnectionRequest-v6e0ext

                            v770NonCriticalExtensions

                                rrcConnectionRequest-v770ext

                                    mac-ehsSupport: true (0)

                                v7b0NonCriticalExtensions

                                    rrcConnectionRequest-v7b0ext

                                    v860NonCriticalExtensions

                                        rrcConnectionRequest-v860ext

                                            pre-redirectionInfo

                                                .... .1.. supportEUTRA-FDD: True

                                                .... ..0. supportEUTRA-TDD: False

 

 

 

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