Where in India is telephone area code 078?

India's telephone area code (or "STD Code") 07677 (international: +91 7677) is for a mobile phonefrom Bihar or Jharkhand state. It is most likely a Reliance Mobile GSM phone, but with number portability an individual subscriber may have chosen a different mobile network provider.

(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.)