Where is telephone country code 770?

+770 is not a valid international calling code. However, +1 770 is a valid area code in North America, serving suburbs of Atlanta, GA, USA.

Telephone country code +7 is Russia and Kazakhstan. A number beginning with +7 70 is a mobile in Kazakhstan.

(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.)