With most providers, you don't need to dial anything to activate roaming. It's entirely automatic.
You dial the U.S. cellphone number exactly the same way you do when it is in the U.S., no matter where in the world it is roaming. The cellular network will automatically find them, and the roaming user will pay any roaming charges, according to their calling plan. The downside is that someone in the UK also has to dial the US number, even when the US cellphone is in the UK.
To call a mobile phone that is roaming in the United States, you dial the number the same way that you would if the mobile is in its home country. The same is true no matter what country you're roaming in.
When a mobile phone is roaming in another country, you dial its number exactly the same way you do when it is in its home country. The mobile network will automatically find the user, and the roaming user will pay any applicable international roaming charges.
Just dial the US cell number, whether the US cell phone is at home or halfway around the world. The cellular network will automatically find the user, if he or she is in a country with a roaming agreement, and the roaming user will pay any applicable fees.
Just dial the UK mobile number. It does not matter that the mobile is roaming in Ireland (or anywhere else); the network will automatically locate the mobile, and the roaming mobile user will pay any applicable roaming surcharges.
That depends. If you are calling a mobile phone with a Fresno number, from a landline in Fresno, you can dial just the 7-digit number. If the mobile phone has a different area code, you will almost always need to dial it, and in many states if the mobile phone is not a local number for you, you may need to dial the area code, even if it's the same as your own.
Yes. If the British mobile user is using international roaming, you should be able to dial the usual UK mobile number; the roaming user will pay the cost of the international forwarding. However, if the British mobile is using an Australian SIM card, you will need to dial the corresponding Australian mobile number.
In most cases, just dial the US number the way you normally would, although the cell phone's owner may pay very expensive international roaming charges, depending on the terms of their contract.
If the US mobile phone is in international roaming mode, you may be able to dial its normal US number. If the phone has swapped in a UK SIM card, you will need to dial the UK number.
Dial the Australian mobile number, exactly the same way that you do when the mobile is at home in Australia. The mobile phone network will automatically route the call to the mobile, wherever it is roaming, and the roaming user will pay any applicable surcharges.
If the American cellphone has a UK SIM card, you dial the UK number associated with that SIM card. However, if the American cellphone is using international roaming, you need to call its U.S. number.
To call from the US to an Australian mobile phone, dial 011 = international access prefix 61 = country code for Australia the Australian mobile number, omitting the leading 0 To call an Australian mobile that is roaming in the US, dial the Australian number as you normally would.