What is the non-DRX timer in GPRS?

Here is some low level detail about the way GPRS works. The non-DRX timer and T3314 are negotiated between the MS and the SGSN during the Attach procedure and then subsequently during Routing Area Updates. The MS can propose values but the SGSN can override these.

T3314 optimisation can reduce paging load considerably. Non-DRX timer optimisation can reduce latency in the downlink.