I assume that you have a line only account under Plan 299.
As I remembered, you can avail a phone under whatever plan you want as long as your credit limit permits after 6 months if you will request thru hotline. If within 6 months, you can just visit any nearest Globe Business Center for the said request.
Note: Please make sure to bring proof of financial capacity (if needed) & a valid id.
I just been 2 months with my line. And plan to upgrade at 499 this 3rd month,.sad to know that i needed to wait for 6 months to get a phone i want.