Yes it will as long as it is GSM and it is unlocked
You can, but it costs extra money from your account.
To call Australia from your US cell phone, you need to dial the international dialing code for the US (which is 1), followed by the country code for Australia (which is 61), and then the Australian phone number you wish to call. Make sure you have international calling enabled on your cell phone plan to avoid any additional charges.
To dial Australia from a US cell phone, you need to first dial the international dialing code, which is 011. Then, dial the country code for Australia, which is 61. Finally, dial the Australian phone number you wish to reach, including the area code.
No - usually the mobile networks will do all the 'hard work' for you.
Most people in the US have a cell phone.
The country prefix for Romania is 0040.
Probably, it depends on where your phone is actually from because the frequencies may not be the same. However, Sprint is a major US cellular carrier and it is likely that your phone will work fine.
In the US it is only AT&T.
If the phone is a world phone that supports overseas frequencies, yes.
Yes you can if you are on a mexican sim card/network. It is possible to text if both are on the same us network but you need signal for that network.
If the headphones work on a PC in the US, then they will work on UK PCs. However if your headphones come from a cell phone, then they will not.
Verizon wireless, Sprint, and ATT