function setReturnValue(txtField1, txtField2, txtField3){

        window.CP_targetInput1.value = txtField1.value;

        if(txtField1.value == txtField2.value) {
        window.CP_targetInput2.value = "";
        } else {
        window.CP_targetInput2.value = txtField2.value.substring(txtField1.value.length, txtField2.value.length);
        }

        window.CP_targetInput3.value = txtField3.value;
        window.CP_targetInput4.value = txtField2.value + txtField3.value;
}

 function insertValue(txtField1, txtField2, txtField3, txtField4) {

            newWindow = window.open('PhoneNumHelpBO', 'newWindow', 'height=150,width=500', false);

            newWindow.document.close();
            window.CP_targetInput1 = txtField1;

            window.CP_targetInput2 = txtField2;

            window.CP_targetInput3 = txtField3;

            window.CP_targetInput4 = txtField4;

  }

function phoneNumberHelp(txtField1, txtField2, txtField3, txtField4) {
  
      if(txtField4.value != txtField1.value + txtField2.value + txtField3.value ) {
          txtField4.value = txtField1.value + txtField2.value + txtField3.value 
      } 
}