A　scheme　is　proposed　for　implementing　the　controlled　phase　gate　for　three　atoms　trapped　in　separated　cavities　coupled　by　optical　fibers.　The　energy-level　distances　of　the　qubit　system　become　unequal　as　a　consequence　of　the　virtual　photon　exchange　between　the　atomic　qubits,　which　allows　the　selective　excitation　of　the　qubit　system　in　the　symmetric　Dicke　subspace.　The　conditional　phase　shift　is　produced　after　a　single　selective　Rabi　oscillation　and　the　operation　is　insensitive　to　cavity　loss　and　fiber　decay.