In The Zone Communications Company - Your Emergency Redundant Communications Dealer! If you can't communicate, you can't recover!

Topics (Click link to jump down)

  • Overview of a Globalstar Phone Call
  • Making a Call via Satellite vs. Cellular

  • Overview of a Globalstar Phone Call

    1. A caller uses Globalstar mode to place a call via the satellite to one or more Gateways
    2. The Gateway routes the call to the existing phone network, in the case indicated below, a cellular Public Land Mobile Network (PLMN) network
    3. The PLMN routes the call to the intended receiver. The call is completed!
    4. The call duration, service used, and service area are reported to the Service Provider for billing.

    Making a Call via Satellite vs. Cellular

     

     

    1. A subscriber in Russia is calling her friend in San Francisco on her Globalstar satellite phone. Her signal is handled by a passing satellite.
    2. The satellite relays the call to a Gateway in its footprint.
    3. The Gateway converts the signal to work with the local PSTN and passes on the call. Depending on the distance between the callers, a Globalstar satellite call might pass through several Gateways and PSTNs before locating the receiving phone. The PSTN uses the call's routing information to connect to another Gateway that knows where the receiving phone is located.
    4. The Gateway located closest to the receiving phone converts the signal to Globalstar format and uplinks it to a satellite. This Gateway knows that the receiving phone is in its contact area because an earlier satellite relayed that phone's power-on registration message to the Gateway. This information was stored in the Gateway's Visitor Location Register (VLR).
    5. The call is relayed to the receiving phone and the call linkage is complete!

    Roaming

    The Globalstar system supports phones that are ANSI-41-based and GSM-based over the common Globalstar Air Interface (GAI). The GAI allows an ANSI-41 user to roam to an area served by GSM or vice versa. The Globalstar Gateway provides the ANSI-41 capability and works with a GSM Mobile Switching Center (MSC) for GSM capability. Each Gateway serving an area governed by GSM contains a GSM MSC.



Although each Gateway includes both ANSI-41 and GSM capability, each type of phone only supports one of these standards. When a subscriber with a Dual-Mode GSM phone roams to North America, his/her phone will operate in Globalstar mode. When the Gateway receives the signal from the satellite, it will be routed to the GSM MSC for processing. The phone will continue to operate using GSM protocols.



 

Similarly, if a subscriber with an ANSI-41 Tri-Mode phone roams to Europe, the phone will operate in Globalstar mode using ANSI-41 protocols.