An EC-GPRS abled MS supports extended coverage where one or more blind physical layer transmissions are used for both Uplink and Downlink. For more information, refer to the 3GPP TS 45.002 specifications information.
EC-GPRS MSs operate in four different coverage classes where each class is approximated with a level of extended coverage compared to GPRS/EGPRS operation denoted as CC1, CC2, CC3 and CC4 respectively.
In Idle-mode, the MS performs a coverage class selection and communicates the selected class to the network. In Packet transfer mode, the network performs the coverage selection and communicates the coverage class to the MS. For Paging, the MS communicates the coverage class to the network when required. For more details on selection procedures, refer to 3GPP TS 45.008  and 3GPP TS 44.018  specifications document.
The MS reports the extended coverage class during system access to the BSS, and the BSS relays the uplink and downlink coverage class of the MS in the UL-UNIDATA BSSGP message. The SGSN stores the coverage class information for the MS and relays it back in all the DL-UNITDATA BSSGP messages towards the MS.
Also, SGSN provides downlink coverage class of the MS in Perform Location Requests, and the MS Radio Access capability with the LCS feature enabled.