G4F (GSM For Fixed)Fixed line on GSM Network Concept
Providing POTS Services in places where local loops do not exist

GSM For Fixed (G4F) solution is dedicated for PSTN/GSM operators who are interested to offer POTS services based on existing GSM/UMTS networks in areas where local loops do not exist and its implementation is unjustifiable due to cost or technical issues. The access to the GSM network is based on DGT 2G/3G Fixed Wireless Terminals.

Any standard POTS analog devices (telephone, fax or modem) can be connected to DGT FWT. The DGT FWT terminal provides standard POTS interface with the whole range of services offered in PSTN network and the phone numbers assigned known to end users are from the number pool of a PSTN network operator not a GSM operator number pool.

               Fixed Network Operator provides:                     Mobile Network Operator provides:

              - All services (including supplementary services)         - Transmission medium between FWT

                for public service requirements                               (user terminal) and DPS controller

              - Billing                                                                - Data transmission using GPRS/EDGE

                                                                                       - Billing for data transmission based on




How does it work 
DGT DPS controller works as a transit-local exchange and is responsible for GSM/UMTS - PSTN numbers and service translations. GSM/UMTS numbers are connected with SIM cards provided by the GSM/UMTS operator while the PSTN operator provides numbers to access POTS services. Depending on the DGT FWT installation place, the SIM cards are connected with the appropriate MSC (Mobile Switching Centre) and then depending on the PSTN “area prefix number” are connected with the given DGT DPS controller.

Any outgoing calls initiated by DGT FWT end-users are always directed through GSM network to the particular DGT DPS controller. Once the mobile/PSTN number translation process is completed, call is routed and presented as the call initiated from the PSTN network. Incoming calls are routed to GSM/UMTS network operator through DGT DPS and dedicated PSTN-GSM/UMTS SS7 trunks. In case of the emergency telephone numbers, DGT DPS controller routes the calls to the particular emergency services supporting a given area.

The main assumption is that PSTN operator acquires from GSM operator a pool of “mobile subscriber lines” (which are reflected in SIM cards) with their support and maintenance service. Received SIM cards are installed in DGT 7400-FWT terminals.

Services Available
The G4F (GSM for Fixed) solution provides national and international voice calls , fax and data transmission – dial-up Internet Access according to current national requirements for public service. Any standard terminals like analogue telephone, fax or modem can be connected to DGT FWT. From the subscriber point of view,  DGT-FWT terminal provides standard POTS interface with the whole range of services offered in a stationary/PSTN network. What is the most important,  the telephone number that is granted is taken from pool of numbers used by stationary network operators.

All the activities within G4F solution are performed by Operational and Management Center(OMC) which provides remote line parameters tests, remote software configuration and maintenanace.

-Remote, rural areas where providing the copper line is technically and/or economically feasible
-African Regions and developing countries with the access to mobile network and with the demand for fix line type services in schools, hospital, small businesses.

For more information:  download DGT GSM For Fixed Catalog Card 



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