The Country Code for India is '91'. The City Code for Hyderabad is '40'. Landline numbers in major cities like Hyderabad, Delhi, Mumbai, Bangalore and Chennai have eight digits, whereas the numbers in smaller cities could have only 4-7 digits. All mobile numbers contain 10 digits and begin with "9" or "8".

Area Codes in India are referred to as STD codes. STD codes for some cities are:

Delhi - 11
Mumbai - 22
Kolkata - 33
Chennai - 44
Hyderabad - 40
Bangalore - 80

In India, both GSM and CDMA (WLL) mobile systems are present. Please contact your mobile service provider in your country to check their roaming partners and tariffs in India. In case you plan on making many local calls in India from your mobile phone, the mobile service provider in your country may be able to provide you with an Indian SIM card. This is a much cheaper way of making local calls as compared with international roaming charges.

Dialing from Outside India into India

1. To Indian Landline
   International access code ('00' or '+"), followed by 91, then STD CODE followed by LANDLINE N°., e.g. +91 44 XXXX XXXX ('44' is the STD CODE for Chennai).
   
   
2. To Indian Mobile International access code ('00' or '+"), followed by 91 and the 10-digit MOBILE N°., e.g. +91 XXX XXX XXXX.

Dialing within India

1. From Indian landline to Indian landline
   Local call: no prefix required for the landline N°.
   Long distance call: 0, then STD CODE followed by landline N°.
2. From Indian landline to Indian Mobile
   Local call -10 digit Mobile N°.
   Long distance call: 0, followed by 10 digit Mobile N°.
3. From Indian Mobile to Indian landline
   Local or Long distance calls: 0, followed by STD Code, followed by landline N°.
4. From Indian Mobile to Indian Mobile
   Local Call - 10 digit Mobile N°.
   Long distance call - 0, followed by Mobile N°.

Dialing out from India to International numbers

The international access code when dialing out of India is "00" (or '+" when dialing from a mobile phone).