This invention relates to communication field and to one method and device of fault user exchanger PBX, wherein, the core of this invention lies in the following: when there is call, under determining PBX at abnormal situation and according to set selection strategy to connect PBX continuous number and recording the said number information. This invention realizes fault PBX interface low cost without intelligent network based on exchange device to realize business automatic tube to ensure PBX fault business lose and PBX user interest to facilitate user.