Each plan includes a certain amount of credits for use and renews each month. These credits are used every time you send a text.
In our system, a SMS uses 1 credit, and MMS uses 3 credits.
If you send longer messages (above 160 characters) it will count as multiple credits.
The larger plan you purchase, the more you save on price (credits are less expensive).
Also, the credits roll over so no worries about using all yours in a month!