Select the correct statement(s) regarding the components of a basic cellular systems (e.g., GSM).

a. all base stations and/or base station controllers are connected to the cellular systems mobile switch which facilitates mobile handoffs between cells, and connectivity to external terrestrial networks such as the PSTN and Internet

b. base stations are directly connected to one another through wireless broadband trunks

c. each base station is equipped with a switch that enables connection to external networks such as the PSTN and Internet d. All statement(s) are correct