When you create a campaign, Member Signal estimates a campaign price. On this step, it just multiplies price per message by the number of recipients with a phone. So you will see something like 105 x $0.03 = $3.15
However, this is not a final price yet.

When Member Signal processes the campaign, it downloads the list of recipients you selected. If you modified the list content, e.g., changed saved search criteria or updated contacts' data, then the list may contain the number of recipients different from what you saw in initial estimation.

Next, the system will examine each mobile number. If the number is invalid or not from the US or Canada, then the system will not try to send a message to it.

Next, the system will try to send a message. But if the recipient opted out before, then you will not be charged for such recipients.

When the system sent all messages, it calculates a final campaign price and adds it to your next invoice.