There are a couple of different ways to read your question.
How do you call someone in Australia from a UK mobile?The telephone country code for Australia is +61, and you must drop the trunk prefix 0 from the domestic number to put it in international format. For example, Sydney's area code 02 becomes +61 2.On any GSM mobile phone, anywhere in the world, you can dial the number in full international format, beginning with the plus symbol.
How do you call a UK mobile when that mobile is in Australia?The physical location of the mobile does not matter in terms of how you dial it. Just dial the UK mobile number the same way you do when the mobile is in the UK. Even if you also are in Australia, you still have to dial the UK number. The country code for the UK is +44, and again you drop the trunk prefix 0 from the domestic number.(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)
If you are calling from a UK mobile to Australia, dial 00 (international prefix from the UK) 61 (country code for Australia) and then the Australian number, dropping the leading 0 To call from Australia to a UK mobile, dial 0011 (international prefix from Australia) 44 (country code for Australia) and then the UK mobile number, dropping the leading 0
you call someone
From a GSM mobile phone, dial +1 310 and the 7-digit mobile number. From a landline, dial 0011 1 310 and the 7-digit mobile number.
The main emergency number in Australia is 000; however, on a GSM mobile phone, you can also dial 112.
If I understand your question correctly. You're in Australia - wanting to call a UK mobile that's been brought to Australia by the British user. You would dial it the same was as if the person was still in the UK. The mobile network knows where both phones are and will route the call accordingly.
Dial 00 61 followed by the Australian number without the initial '0'. From mobile telephones you can also dial: + 61
Just dial the UK mobile number as normal. The network will sort out the logistics.
To call an English mobile that is roaming in another country, dial the English mobile number exactly the same way you would if the mobile were in England. English mobile numbers begin with +44 74 through +44 79. On a GSM mobile, enter the number in international format, beginning with the plus sign. Otherwise, replace the plus sign with your international access prefix (most commonly 00, but many countries use other prefixes. Australia uses 0011 and other prefixes.).
To call an Australian mobile phone, you dial the Australian mobile number. It does not matter if the mobile phone is physically in Australia, Honolulu, or anywhere else.
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.
Replace the trunk prefix 0 of the Thai number (mobile or landline) with telephone country code +66, including the plus symbol.
Dial 0061 (the international access code for Australia) - then the number in full.