MetroPCS doesn't have its own area code. Mobile phones in the US and Canada generally use the same geographic area codes as landline telephones. In fact, you can "port" a mobile number to a landline or vice-versa, so mobile and landline numbers are completely indistinguishable.
Landline phones in Dalbeattie are most likely in the 01556 area code (or +44 1556 from overseas).
Ask your local phone company.
Germany: Landline - 49 Cell - 4917
Dial 00 353 and then the landline with its area code and leaving out the first zero.
Dial the full number - including the area code.
In the UK, area code 020 is for landlines in London. 84 would be the first two digits of an eight-digit local number.
In the U.S. and Canada, there is no area code 643, and telephone numbers for cellular phones are intermixed with landline numbers in the same geographic area codes.
From a landline, dial 00 1 and then the area code and number. From a mobile phone, dial +1 (including the plus symbol) and then area code and number.
To dial any number in the US (landline or mobile) from the UK, dial 00 1 followed by the area code and number.
It is quite common in the U.S. for a person to have a cell phone with an area code from somewhere other than where they currently live. To have a landline with a different area code is much more difficult and expensive.
You would dial the international access code (usually 00) then the country code for Australia (61) then the subscribers number (including area code)