Or (to add to Marc's suggestion), have you tried:
<FieldRefName='CurrentPhase' LookupId='True'/><ValueType='Lookup'>3</Value>
Assuming that the item '3 - Planning' is actually the record with ID = 3.
_________
Paul T
_________
Paul T
<FieldRefName='CurrentPhase' LookupId='True'/><ValueType='Lookup'>3</Value>