When you need to include a link in your SMS, the Short Trackable Links feature will automatically shorten any URL to 22 characters.
STL Feature Activated
If you have the feature activated on your account, when you add a link to your message you'll see a note telling you it's been shortened. This means your character count will only increase by 22 characters, regardless of how long the link is that you're adding.
STL Feature Not Activated
If you don't have the feature activated on your account, when you add a link to your message you'll see a note telling you the feature is disabled. This means your character count will increase by the length of the link you're adding, so if it's a long one, your message may span multiple parts - not ideal when you're sending larger broadcasts as they'll cost more than they need to.