A performance evaluation of GSM service providers (Globacom, MTN and Zain) was conducted in Okada, Edo State; home of Igbinedion University. The main research objective was ascertaining the Quality of Service (QoS) provision level and fulfillment of minimum industry QoS standards of GSM operators. The GSM Key Performance Indicators (KPIs) and technical parameters measured included: percentages of call set-up success rate, call set-up failure rate, post dialing delay (intra/inter-network), call drop rate, call retention rate and call completion rate; credit balance inquiry success and failure; SMS delivery failures, incorrect feedback and multiple billing; recharge cards loading success, loading error and loading incorrect feedback. The measurements were carried out at different geographical positions of the town at varying time intervals. Observations were also made on some other performance issues like network availability, voice quality, call setup phase, post dialing delay-elongation, weather influence and signaling/ feedback. The study revealed several levels of KPI achievements by the different networks with Globacom performing best, coming tops in twenty-three (23) indicators out of the thirty-seven (37) considered followed by Zain and then MTN. It also revealed that the networks achieved some NCC QoS benchmarks and failed in some other notable ones.