Is this possible with Campaigns?

Is this possible with Campaigns?

My company is  currently moving CRM's from Monday to Zoho One. Currently, our marketing lead process is send out 7 sms messages over 14 days if the lead is in a certain status. If we don't get a response the lead is put into a "Closed" status. 

Do we buy numbers from Zoho or where are the sent numbers from?

Would this be better done with Zoho Flow, or with Schedules/Functions.?

Thank you for your insights!