The study examines the network variability of GSM in Oyo, Oyo State, Nigeria using MTN, Globacom, Airtel and 9Mobile networks. The requisite data is composed through the drive test technique. Four infinix cell phones are installed on Network Signal Info software to enable per minute logging of the lunched signal strength and quality. The composed data were keyed into Statistical Package for the Social Sciences (SPSS) computer software for quantitative analysis. The network signal variability is substantiated using one way Analysis of Variance (ANOVA) for data analysis of signal strength and quality. The results show signal strength and quality average values of -66.59 ,-76.59 ,-86.29 and -92.78 likewise 84.26, 64.28, 44.48 and 42.54 for MTN, Globacom, Airtel and 9Mobile network systems respectively. The result shows that the signal quality variability in MTN, Globacom as well as Airtel network in the study area was not statistically significant as . This justified the fairly dissemination of MTN, Globacom and Airtel signal quality and its inconsequential variations across the entire city of Oyo Town. Conversely, the variation in quality of 9Mobile network shows statistically significant values as . The feeble signal quality results to poor communication and calls distortion across the research areas. The study affirms that MTN and Globacom are the best networks for transaction at Oyo followed by Airtel and 9Mobile. The study hereby recommends the installations of relevant facilities and Base Transceiver stations (BTS) to improve the strength and quality of the mobile network signals in Oyo Town