Whenever i create a new record make phone as mandatory for first time only once we edit and delete the phone data it should not show the error how to do that?
You should be able to make use of the ISNEW() function in your formula to condition the validation logic. More details here : https://www.salesforce.com/us/developer/docs/pages/Content/pages_variables_functions.htm
You should be able to make use of the ISNEW() function in your formula to condition the validation logic.
More details here : https://www.salesforce.com/us/developer/docs/pages/Content/pages_variables_functions.htm
HTH