ve point-to-point packet data units (PDUs) in this state. The network initiates no GPRS pages for an MS in the READY state, but pages for other services may be done via the SGSN. The SGSN transfers downlink data to the BSS responsible for the subscriber's actual GPRS cell. The MS may activate or deactivate PDP contexts while in the READY state. Regardless of whether a radio resource is allocated to the subscriber or not, the MM context remains in the READY state even when there is no data being communicated. A timer supervises the READY state. The MM context moves from the READY state to the STANDBY state when the READY timer expires. In order to move from the READY state to the IDLE state, the MS initiates the GPRS detach procedure. Paging for GPRS Downlink Transfer An MS in the STANDBY state is paged by the SGSN before a downlink transfer to that MS. The paging procedure will move the MM state to READY to allow the SGSN to forward downlink data to the radio resource. Therefore, any uplink data from the MS that moves the MM context at the SGSN to the READY state is a valid response to paging. The SGSN supervises the paging procedure with a timer. If the SGSN receives no response from the MS to the paging request message, it will repeat the paging. The repetition strategy is implemented using the parameter RA paging repetition (RPR), which is set to 3 seconds as a default. The number of repetitions is dependent on the parameter RA paging area (RPA) (1-5). If the MS has still not responded, the page is sent to the whole SGSN paging area. The parameter SGSN paging area defines the maximum number of SGSN wide pages. The MS will accept pages also in the READY state if no radio resource is assigned. This supports recovery from inconsistent MM states in MS and SGSN. The paging procedure is illustrated in Figure 2.39: The SGSN receives a downlink PDP PDU for an MS in the STANDBY state. Downlink signalling to a STANDBY state MS initiates paging as well. The SGSN sends a BSSGP (Base Station System GPRS Protocol) Paging Re