what were the suggestions from the school?

How does your son get to school? Bus? Bike? driven by ex?

truancy will be filed on your son if this is a common occurance
you will go to court if that happens
you will face jail time or fines

this is the law

some courts push probation and some do not

I have known parents to have to go to jail

looking forward to seeing your son is great

texting him this is fine but perhaps letting him know that skipping school is not acceptable and consequences will happen because of that
and then
enforce them

how important is that cell phone to him?
important enough to go to school and shape up?

I know it is for my son

how important are any extra-curriculars (which he should be benched from now anyway)
or
hanging with friends
or
curfew
or
freedoms

you aren't his buddy or his friend
you are his parent