Error 303 - (אין הרשאת סולק לביצוע עסקה כאשר הכרטיס לא נוכח (טלפונית is an error received from shva, the error reflects that the current configuration of your terminal does not allow "e-commerce transactions", but "telephone transactions" only.
This configuration for telephone/ e-commerce transactions is set through your credit card company.
In the credit card company configuration, there are two main options that refer to this issue:
Signed and telephone transactions only - 2
Signed, telephone and internet transactions - 3
Once the configuration will be changed to "signed, telephone and internet transactions - 3" on the credit card company side, the problem should be solved.