If you have no sufficient credit to make a call, you can send a request to the number you’re about to call through the Vodafone Call Me Back service:
1.Enter the menu #123# and through the option CallMeBack you may notify for free the Vodafone number you’d like to call . The receiver of the request will be notified about your request via SMS
2.Send an SMS for free towards 144 with the text “ Please call me_(Space)_(the number of the person you want to call you back).
Example: Please call me 06XXXXXXXX
You may send up to 8 requests per month (a maximum of 4 per day).