Polling campaign is consists of a single question with either multiple choice or open-ended response.
Every time our system sends out a text message of 160 characters or 70 characters in case of a text message contains Non-GSM characters (Unicode), from your campaign, it considers a one text credit.
If you have an audience of 500 people and if everyone is going to cast a vote, you need at least 500 text credits assuming the vote confirmation message is under 160 characters.
Read More about Non-GSM characters (Unicode) Characterset at the following links: