Dial +1 (including the plus symbol), followed by the 10-digit US telephone number.
You would dial 001 followed by the area code and subscriber's number.
If you are in the US, Canada, or various Caribbean-ish islands that are part of the North American Numbering Plan (country code +1), you just dial 1 + area code + number. If you are elsewhere in the world, dial your international access prefix, followed by the country code 1, area code, and number.
If it's country code +234 (Nigeria), dial the international access prefix (011 from the US), country code 234, and the Nigerian number (omitting the leading zero). If it's area code +1 234 (Akron/Canton/Youngstown, OH), dial "one-plus"
The telephone country code for North America (US, Canada, and several island nations and territories in or near the Caribbean) is +1. The plus sign means "insert your international access prefix here." The international access prefix from Cameroon is 00, so to call the US, dial 00 + 1 + area code + number. (To call from the US to Cameroon, dial 011 + 237 + 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.
You dial +1 011 1 followed by the number you wish to contact. +1 is the country code for the US, 011 is the IDD International Prefix and 1 is the NDD National Prefix
To call Kabul, Afghanistan, from the US, dial 011 = international access prefix from the US 93 = country code for Afghanistan 20 = city code for Kabul (020 from within Afghanistan) and the 7-digit local number
The country code for the UAE is +971, and you must drop the trunk prefix 0 from the UAE domestic number. On a mobile phone, just dial in full international format, beginning with +971, including the plus symbol. Otherwise, replace the plus symbol with the US/North American international access prefix 011.
In your question, it looks like you didn't dial all the digits. A UK mobile phone number, as dialed from a US or Canadian landline phone, is of the form 011-44-7AXX-XXXXXX-#, where A=4,5,7,8,9 and X is any digit. Pressing the # key at the end tells the telephone switch not to wait for any more digits. More generally, to dial any UK telephone number from the US, substitute the prefix 011-44 for the trunk prefix 0 of the UK domestic telephone number.
You dial the UK mobile number exactly the same way you do when it is at home in Britain. The mobile network automatically re-routes the call for you.From a UK landline, you dial 07...From a GSM mobile anywhere in the world, dial +44 7...From a US landline, or from a US non-GSM mobile, dial 011 44 7...From the rest of the world, dial your international access prefix, then 44 7...(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.)
On a mobile phone (cell phone), just dial +34 (including the plus symbol) and then the 9-digit Spanish telephone number. On a landline, a fax machine, or a cell phone that does not allow you to enter the plus symbol in a telephone number, replace the plus symbol with the US/North American international access prefix, 011.