And also do i have to buy a specific pc mobile phone in order to do this?And one more concern is, how do i use my phone in the US and can i keep my remaining minutes from one month to the next if i use the US availability?"
Along with your phone number, PC Mobile will transfer your existing account credit balance to your new PC mobile phone. Once you purchase a new PC mobile phone; to keep your existing number, plan and active funds, simply contact PC Mobile customer service centre at 1-877-284-6361 and a PC mobile representative will assist you.
Due to technical issues, PC Mobile is temporarily unable to activate prepaid roaming for the United States for PC mobile accounts. They expect to have the issue resolved shortly, and would be happy to send you a text message to inform you when the service is available. To receive their text alert, please contact their customer service center. source