Also known as: GPRS, General Packet Radio Service, 2.5G
GPRS (General Packet Radio Service) is the packet-switched data upgrade to GSM, often called 2.5G. Instead of tying up a whole circuit for the duration of a session, GPRS pools spare TDMA time slots and hands them out packet by packet, giving handsets always-on IP connectivity for web browsing, email, and WAP at a few tens of kilobits per second.1
Overview
Circuit-switched GSM data (CSD) reserved a whole time slot for an entire call, which suited voice but wasted capacity on bursty Internet traffic. GPRS instead treats one or more slots as a shared resource: a device grabs slots only when it has packets to send, and multiple users are multiplexed onto the same slots. A handset can bond several downlink slots for higher throughput, and coding schemes trade error protection against speed as radio conditions vary.
Technical characteristics
| Property | Value |
|---|---|
| Generation | 2.5G |
| Access | Packet-switched over shared GSM TDMA slots |
| Modulation | GMSK (as GSM) |
| Coding schemes | CS-1 to CS-4 (≈8–20 kbit/s per slot) |
| Multislot | Up to several slots bonded per direction |
| Typical rate | 30–80 kbit/s in practice |
| Core network | Adds SGSN and GGSN packet nodes to GSM |
Data sessions are described by a PDP context that maps the device onto an external IP network; billing shifts from per-minute to per-megabyte.
History
GPRS was specified by ETSI in the late 1990s and reached commercial networks around 2000, later maintained by 3GPP. It was the first mass-market always-on mobile data service and the foundation for the faster EDGE enhancement that followed, which kept the same packet core but swapped in higher-order modulation.
Deployment
GPRS rode on existing GSM spectrum, so operators could enable it with software and core-network upgrades rather than new radios. It powered early mobile Internet, MMS, and machine-to-machine telemetry. As 3G and 4G arrived it became a low-rate fallback, and it still serves undemanding IoT and metering devices where 2G networks remain switched on.
Decoding it with GopherTrunk
GopherTrunk targets land-mobile and utility signals; cellular packet data such as GPRS is out of scope and is not decoded. GPRS traffic is authenticated, operator-licensed, and typically ciphered, and it rides the same private GSM carriers. It is listed here only for reference within the cellular family.
Sources
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General Packet Radio Service — Wikipedia, for the 2.5G GPRS packet-data service, its shared-slot operation over GSM, and its coding schemes. ↩