Why am I being charged extra?

The deduction depends on the target country to which you are sending SMS communications.
Possible reasons for extra charges are listed below:

1. Missing country code
   
   If you do not add the country code, the starting digits of the mobile number, detected as a country code. Charges are then applied accordingly.
   
   For more details, refer to this document. https://msg91.com/help/credits/credit-count-for-different-countries
   

2. Message length
   
   Even if you send SMS with the correct country code, extra charges may apply based on the length of the message content (SMS segments).
   
   For more information, refer to this document. https://msg91.com/help/more/what-is-the-character-limit-for-a-single-credit-in-english-unicode-how-is-credit-calculated