Got this working late last year, received a request from someone working in Glo customer care to provide my solution so here it is for y'all to try
By default, the iPhone has room only for entering APN, Username and Password for GPRS/Edge settings. It's relatively easy to configure it for GPRS on carriers that don't require port or proxy to work (Celtel, Mtn). However. Glo's GPRS settings needs you to input a proxy (10.100.98.22) and a port (3130) hence no GPRS love for Glo iphone users.
Here's a solution
Download and install iPhoneBrowser
http://iphonebrowser.googlecode.com/files/SetupiPhoneBrowser.1.52.exeDownload and Unzip this package
http://www.sendspace.com/file/e75g3jit contains two files,
proxy.pac and
preferences.plistSimply open iPhoneBrowser, use it to upload
proxy.pac to
/private/var/rootand
preferences.plist to
/private/var/root/Library/Preferences/SystemConfiguration/Finally, on your iPhone go to Settings> General > Network > Edge and enter the glo APN, username and Password
As far as i know, it's
APN: glogwap
user: wap
password: wap
That's it! Lemme know if there are any issues.