The present disclosure presents a method and an apparatus for searching for service when a multi-mode UE goes out of service (OOS). For example, the disclosure presents a method for receiving a request to scan frequencies of a RPLMN of a first RAT and scanning the frequencies of the first RAT based on an acquisition database (ACQ DB). In addition, such an example method, may include sending an available PLMN list to the NAS layer, switching to a second RAT based on a request from the NAS layer, scanning frequencies of the second RAT based on the ACQ DB, and camping on a frequency of the second RAT found during the scanning of the frequencies of the second RAT based on the ACQ DB. As such, a method and an apparatus for searching for service when a multi-mode UE goes OOS may be achieved.