1. Buy Glo Data Plan via Glo HSI Portal
You can buy glo MB at Glo HSI Portal at hsi.glo.com.
I use this portal alot especially whenever I want to subscribe to glo data plan on my iPad. If you've recharged your glo line, you can access the Glo HSI page on your device to buy your desired plan. Just click on the "BUY" icon next to the plan you want to purchase and you are good to go.
The Glo HSI portal works on other mobile devices and also on computer if you connect with a modem with a Glo line in it. You can also gift and share glo data plans at the HSI Portal.
2. Buy Glo Data Plan Via SMS
Each glo data plan has a string you can text to 127 with your glo line, for you to be subscribed to the plan. For example, to subscribe to Glo Always Micro Plan (N1000 for 30days) via SMS, you will have to text 53 to 127 with your glo line.
3. Buy Glo Data Plan via USSD
Instead of sending text messages to 127 to buy a glo data plan, you can as well dial a string to get hooked up to the glo data bundle of your choice. For example, to subscribe to Glo Always Micro Plan (N1000 for 30days) via USSD, you will have to dial *127*53#.
Kindly note that you must have enough airtime in your Glo line main account balance, if not you won't be able to buy MB from Glo.
You can check the full list of all glo data plans and their codes here.