If by grace period you mean the time in which you can return the phone and cancel the plan without paying anything.
Yes but its very limited.
You have 30 days from the day you started the plan to return the phone and cancel the plan without fees . HOWEVER
the conditions being
A) The phone needs to have less then 15 minutes of talk time
B)you need to have everything that came with the phone in mint condition
C)You may still be charged a restocking fee , however depending on your attitude you might get to waved