Before choosing GSM or any other type of air interface (GSM, CDMA, TDMA, AMPS, DECT, PHS, ad nauseum) you should consider your requirements. If offering telephpony service over a limited area to slow-moving terminals (like pedestrians) is important, WiFi or WiMax or other technologies might offer sufficient capabilities to meet those needs.

GSM and other multiple access (the "MA" in CDMA and TDMA) technologies impose a high cost to provide mobility that must scale from pedestrians to automobiles and trains, etc., moving at 200 kmph and faster. This cost is for hardware and software in HLR, VLR and BTS components and others.

If your requirements do not require high-speed mobility, meaning you target terminals which move at human speeds around a limited geographic area like a campus, investigate limited mobility solutions using unlicensed spectrum such as WiFi and WiMax, and using off-the-shelf and Open Source technologies.

You may have to build from the ground up, but as a university your labor pool should be relatively inexpensive, and hardware, too, should be affordable.

Good luck. Please remember to let the readers of SlashDot know what you choose to implement, and your experience doing so.