A default donation amount is the amount that the supporter will donate via text, if they do not specify a number after the keyword in their message that they send to donate.
If you set a default donation amount on your campaign, this means that the supporter just has to text the KEYWORD to the shortcode phone number to make a donation of that amount. For instance, if you set your keyword as DONR on the shortcode 70085, with a default donation amount of £5, a supporter would text ‘DONR’ to 70085 and donate £5.
However, they can still donate any other amount between £1 and £20 by specifying a number in their text message – texting ‘DONR 3’ to 70085 would donate £3.
If you do not specify a default donation amount, and the supporter does not specify a donation amount in their text message, they will receive a bounce-back message asking them to do so.