Hello @Marita11,
You don't say whether the calls are from guests renting the property for which you're a co-host or for your own properties. If the calls are from renters of the co-hosted property then it may be that the host has to remove your phone number.
Irrespective of whether the renters are for the co-host property or your own properties you don't say whether they are renters with reservations confirmed before you removed your number or whether they made the reservation afterwards.
If the calls are from people with reservations confirmed before you removed your number then they can call you as they received your number at the time that their reservation was confirmed.
If they are for new reservations made after you removed your number then contact Airbnb as they may still give out the number you used when originally registering your account.
changing phone notification options affects only how Airbnb administration communicates with you, it won't by itself stop guests getting your number or being able to contact you by phone.
Steve.