A lot of possible things can happen. One of which, you will have a derogatory record with Globe for that deliquent account. Once you have that record, this will cause you inconvenience in the future should you wish to apply again with Globe. The deliquent account will prevent you from opening new line unless you settle that account.
Second, the deliquent account will be forwarded to a collecting agency incurring additional expenses which will be added to your account. The collecting agent will do his utmost capacity to collect from you up to the point of harassing you through phone calls or sms or emails. Expect those as it is their means of collecting from you. You won't be charged in any court for this as filing a case for collection is more expensive than the amount being collected.
Nonetheless, i am not condoning you not to pay your obligation but for your own good, considering that you signed a contracf with Globe, you commit yourself to abide by it and finish it. I understand that for lack of money as we encounter this in our lives, we have difficulties in our payments but Globe can offer you other remedies for you to pay and fulfill your contract.
Be reminded that if the reason for your non payment is due to Globe's in ability to perform what is stated in the contract, you have the right to terminate the contract even without the end of it. Otherwise, kung talagang walang pambayad then wala na po magagawa jan. Expect lang po that your name will be added on Globe's deliquent accounts.