00 is a common international access prefix, and +1 is the country code for North America (USA, Canada, and 18 Caribbean-ish islands). Area code +1 877 is domestic toll-free numbers in North America. Calling from outside North America, the call may go through with the caller paying ordinary international toll rates, or the call may fail.
Alternatively, in some areas, the international access prefix is 001, which would leave country code +877, which is assigned for some future maritime mobile telephone service. It is best to quote an international telephone number beginning with the plus sign and country code, omitting any access prefix.
(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.)
The telephone country code 00 790 is not a valid country code. The prefix "00" is often used as an international dialing prefix in many countries, but "790" does not correspond to any specific country. If you meant to ask about a different code, please clarify.
Ciudad Acuña, Coahuila, is in Mexican area code 877. From outside Mexico, dial your international access prefix (00, 011, etc.), then country code 52, then a 1 if you are dialing a mobile phone, then area code 877 and the 7-digit local number. MOBILE: +52 1 877 123-4567 LANDLINE: +52 877 123-4567
There is no telephone country code +302. To call Greece (telephone country code +30) from Saudi Arabia, you dial 00 30.
00 isn't part of the country code, it is a commonly used international access prefix. Country code +801 does not exist.
'00' is not part of the country code, it is a commonly used international access prefix. Country code +256 is Uganda, and +256 78 is a mobile.
'00' is not part of the country code, it is a commonly used international access prefix. Country code +90 is Turkey, and +90 542 is a Vodafone mobile.
'00' is not part of the country code, it is a commonly used international access prefix. Country code +221 is Senegal, and +221 76 is a Sentel Tigo mobile.
00 isn't part of the country code, it is a commonly used international access prefix. Country code +91 is India, and +91 9269 is a mobile phone in Rajasthan.
'00' isn't part of the country code, it is a commonly used international access prefix. Country code +49 is Germany, and +49 15 is the beginning of a mobile number.
Country code +225 (dialed as 00225 from many places) is Cote d'Ivoire (Ivory Coast), but there are no numbers beginning with +225 00, although there are some numbers that begin with +225 0.
There are no countries currently using telephone country codes that begin with a zero.00, 001 and 011 are common codes used to dial out of a country and start an international call. The country code comes after this.Examples:011 is the international access code used in the USA and 44 is the country code for the United Kingdom. So, 011 44 would be dialled to call from the USA to the UK.00 is the international access code used in Ireland and 61 is the country code for Australia. So, 00 61 would be dialled to call from Ireland to Australia.00 is the international access code used in the United Kingdom and 353 is the country code for Ireland. So, 00 353 would be dialled to call from the UK to Ireland.
'00' isn't part of the country code, it is a commonly used international access prefix. Country code +61 is Australia, but there are no valid numbers beginning with +61 0. Conclusion: invalid code.