does sms/test sent in sandbox account go to real phone numbers..?

i was testing my python code (to send sms) i was using to similuate but using the data from the main database but i did created the variables with giving my sandbox as sender and my main number as reciever number but in other part of code due to looping part the code might have picked up the data fromthe main database.so should i be worried about the msgs going to real numbers or as it is sandbox account the msgs will not be sent?