Currently SMS Template allows about 500 characters.
However it is recommended to use smaller messages of max 480/490 characters.
It is possible that Template gets created and even be sent for approval - however one would notice the message is truncated as per the limit.
Advise Users not to use special characters like <> as having these in content could cause issues with SMS truncation.
Say someone creates a template as" Thank you for contacting us - please express your consent by replying <YES> to 53535 etc.
You'd notice that the SMS Breaks before the angular bracket and the message gets delivered until the word before the special character [...replying ]
Instead of Angular brackets - they could be advised to use [ ] square brackets - these work fine.