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Emergency Call Frequency

Viewing 13 posts - 1 through 13 (of 13 total)
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  • #61361 Reply
    Jason
    Guest

    Hi all,
    Is there any special band of frequency for emergency calls? Or they use any available network in the area…

    #61362 Reply
    Pix
    Guest

    For the part (a) I am not sure, so any expert is welcome to confirm…

    a) the MS will select any network available, from any operator, as long as there is a roaming agreement between them.

    b) To force the MS to “select” any operator, remove the SIM card. Then the MS is in “emergency” mode. (this i know because i tried it 🙂 )

    #61363 Reply
    Jason
    Guest

    What if MS is out of any operator coverage??
    I mean if you go to a location which has not been covered by any operator will you be able to make emergency calls? If yes then which frequency(ies) will the MS use??

    #61364 Reply
    Pix
    Guest

    Jason,

    Unfortunately, GSM is not magic… If there is no operator covering the spot where you are, you are in deep trouble ! MS can only use GSM/DCS frequencies, nothing else.
    Only “Satellite phones” have a global worldwide coverage.

    #61365 Reply
    sha
    Guest

    Hi Pix,

    Can u pls give the sequences involved in emergency call setup.

    #61366 Reply
    paraHO
    Guest

    Looking at MS-BTS / BTS-MS. It should not happen with multiple networks (850/900/1800/1900MHz) providing in an area, but don’t forget to check whether “Access Class 10” is broadcast (BTS-MS = point-to-multipoint) as well.

    #61367 Reply
    Pix
    Guest

    ParaHO, could you elaborate please ?

    Sha,
    It is a standard cal call setup, nothing special about it,

    pix

    #61368 Reply
    paraHO
    Guest

    PIX

    For Phase 1 the standard
    GSM0211
    4. ACCESS CONTROL
    As regards Emergency calls (i.e “Class” 10), see note 2.

    Note 2: This means that MSs in class 0-9, or without a valid IMSI, are not allowed to make emergency call attempts if “emergency call class” is barred.

    For Phase 2+ the standard reads:
    GSM0211
    4.4 Emergency Calls
    An additional control bit known as “Access Class 10” is also signalled over the air interface to the MS. This indicates whether or not network access for Emergency Calls is allowed for MSs with access classes 0 to 9 or without an IMSI. For MSs with access classes 11 to 15, Emergency Calls are not allowed if both “Access class 10” and the relevant Access Class (11 to 15) are barred (GSM 04.08 [6] refers). Otherwise, Emergency Calls are allowed.

    I am just pointing out that in some countries it may be Phase 1 systems might still operate, but where Phase 2+ is relevant it still doesn’t automatically follow that emergency calls will be allowed.

    In fact even handset manufacturers may not be entirely sure what facilities a mobile network may provide. The Nokia 6303 syas this:

    Emergency calls
    Important: This device operates using radio signals,
    wireless networks, landline networks, and user-programmed
    functions. If your device supports voice calls over the internet
    (internet calls), activate both the internet calls and the
    cellular phone. The device will attempt to make emergency
    calls over both the cellular networks and through your
    internet call provider if both are activated. Connections in all
    conditions cannot be guaranteed. You should never rely
    solely on any wireless device for essential communications
    like medical emergencies.

    To make an emergency call:

    1 If the device is not on, switch it on. Check for adequate
    signal strength. Depending on your device, you may
    also need to complete the following:

    • Insert a SIM card if your device uses one.
    • Remove certain call restrictions you have
    activated in your device.
    • Change your profile from offline or flight profile
    mode to an active profile.

    2 Press the end key as many times as needed to clear the
    display and ready the device for calls.

    3 Enter the official emergency number for your present
    location. Emergency numbers vary by location.

    4 Press the call key.
    When making an emergency call, give all the necessary
    information as accurately as possible. Your wireless device
    may be the only means of communication at the scene of an
    accident. Do not end the call until given permission to do so.

    #61369 Reply
    Pix
    Guest

    ok, indeed in alcatel, there is a parameter called EMERGENCY_CALL

    Indicates if Emergency calls are allowed for all access classes or only for access classes 11 to 15.

    0: all access classes, 1: access classes 11 to 15 only

    By default, it is zero 🙂

    Thank you, paraHO !!! Great info, as usual.

    #61370 Reply
    paraHO
    Guest

    Thanks PIX 🙂

    Just add some more info (not sure it will help):

    In UK use 999 (Emergency Services) and use E-112 (EU Emergency Services code allocation). However dialling 911 (US Emergency Services number) on MS, calls routed UK operator when MS located in UK. Not tried 911 when no SIM in ME.

    #61371 Reply
    nobsophanit
    Guest

    How many frequency of emergency call?

    #61372 Reply
    Lance
    Guest

    What frequency does the US use for emergency cell phone calls? Do they have a particular frequency range that differs from regular cell phone calls?

    #61373 Reply
    pix
    Guest

    hi lance,

    no, emergency calls are using the same cell towers, same equipment and same frequencies than regular calls.

    pix

Viewing 13 posts - 1 through 13 (of 13 total)
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