Note that you can recharge with any denomination (N100, N200, N500).
Glo subscribers can load recharge cards from different countries that their service provider operates in, and communicate using the tariff plan of the country they reside in currently. For example; if you travel to Benin Republic and purchase a Glo line, you can recharge that line using a Glo Nigeria recharge card.
I decided to share this information because I noticed a lot of Nigerian students here in Benin Republic still find this confusing. They keep asking this question, while some accidentally got their lines barred for multiple trials.
You can either load the card using the PIN that was sent from Nigeria or simply purchase and load the card from Nigeria, it would work either way. Most people recharge using the card pins sent to them from Nigeria.
How to load Glo Nigeria Recharge card on Glo Benin Line
You can do this by dialing *123*234*PIN#, After you load the card, it would automatically be converted into the local currency, for example, A N500 Glo recharge card would be converted to 1800CFA(Depending on the current exchange rate) in a Glo Benin line.