A method, a related apparatus, and a system for recovering a called service of a terminal are provided. The method includes: when a called request of a user terminal is received, querying an initial proxy-call session control function (P-CSCF) entity with which the user terminal currently registers; if it is detected that the initial P-CSCF is faulty, selecting an available P-CSCF and sending, to the available P-CSCF, a notification message that carries a redundancy identifier, where the redundancy identifier is used to instruct the available P-CSCF to trigger the user terminal to re-register with the P-CSCF; and when a registration complete message sent by the P-CSCF with which the user terminal re-registers is received, delivering the called request to the re-registered P-CSCF to bear a called service of the user terminal.