Verizon Cell Phone account Question?

I have zero credit as i dont own any credit cards....my gf who has bad credit 511 wanted me to sign up for a plan of 79.99 with verizon. she couldnt get the cell phone cuz they would hv required a deposit of $1000 from her. Instead I signed up for the acct even tho i didnt have credit with a $400 deposit (My gf paid for everything). She pays the monthly bills and its a 2 yr contract. What happens if she doensnt pay the bill on time or the account becomes delinquent....would that affect my credit??? Would i be imposed a fine or penalty for non payment? Remember i dont have any credit whatsoever...i called equifax to get my report ....and they have no record of me. Please advise. THanks.