Yes, both owners and renters can exchange phone numbers for easier and more detailed communication. Those details are also available on the booking voucher that both owners and renters receive as soon as a payment is made to secure a reservation.
It is recommended to still communicate through the platform, as this will ensure a good record of the conversation, in case any miscommunication problems arise later.
Communicating through the platform will ensure that all transactions are properly monitored for your protection.
Note however that as per section 9.5 of the Terms of Service, an owner cannot redirect RVezy renters out of either another rental platform or any other rental services.