What is considered a message in the chats for pricing?

When using the chats, a message is a maximum of 160 characters. When people use 160 or less charcaters, they will be charge for only one message. As soon as they use more than 160 characters in a single conversation, they will be charge for additional messages accordingly to the number of characters sent (every 160 characters, a new message is invoiced).

For example, if your price per message is $2 and another user sends you a message of 200 characters, you will be a able to charge $4 (2 messages x $2) as soon as you reply as that person sent you more than 160 characters (over 1 message) and less than 320 characters (which would be over two messages and will start counting for 3 messages).