FG-D

FG-D access is designed to provide equal transmission performance (as perceived by the EU) between the POT and the EO, whether routed directly or via an AT. FG-D provides higher quality services than the other Feature Groups. It is known as equal access because it guarantees that all carriers are processed equally. It defines interconnection rules between a LEC and an IC. FG-D services route inter-LATA calls to the IEC POT, route calls with a CAC to the user's carrier, and pass information to the carrier. Information passed includes the caller's number, through ANI.






FG-D Service Description:


The voice-transmission path between the POT and an EO ranges from 300 to 3000 Hz, provided by the LATA access for FGD. Stored Program Controlled EO or an AT switch allows trunk-side switching, which provides access to LATA. Analog parameters for FGD access are specified from POT to EO. The transmission parameters are stricter when routing is done through an AT than those for other feature groups or direct FG-D access. Figure below illustrates these features. Note that the more stringent transmission type A1 parameters are provided on both the dedicated transmission path from the POT to the AT and on the common transmission path from the AT to the EO. Transmission type B1 is provided between the POT and the EO for FGD direct access. FGD service terminating in the LATA has access to NXXs and miscellaneous services as well as other ICs’ services, if they can be reached using NXX codes. Calls originating from the LATA reach the desired customer by the uniform access code of the form 10XXX. (When Carrier Identification Code-Expansion [CIC-E] becomes effective, the uniform access code will be in the form of 101XXXX.) No access code is needed if the end user’s telephone exchange service is arranged for presubscription. In the terminating direction, FGD may not be switched to FG-B, FG-C, or FG-D.




Key Words:


LATA – Local Access and Transport Area
LEC – Local Exchange Carrier
IC – Inter Exchange Carrier
POT – Point of Termination
CAC – Carrier Access Code
ANI – Automatic Number Identification
EO – End Office
CCS – Common Channel Signaling
SS7 – Signaling System 7
IG – Interface Group
PSDS – Public Switched Digital Service
ISDN – Integrated Services Digital Network
DEOT – Direct End Office
NANP – North American Numbering Plan