The objective of this paper is to examine a model to identify Social Engineer Attack Phases to improve the security countermeasures by Social-Engineer Involvement. A questionnaire was developed and distributed to a sample of 243 respondents who were actively engaged in 3 Jordanian telecommunication companies. All hypotheses were tested using (PLS-SEM). The results of the study indicate that Social Engineer Attack Phases (Identification the potential target, Target Recognition, Decision approach, and Execution) have a partially mediate and significant impact on improving the security countermeasures by Social-Engineer Involvement. On the other hand, the Social Engineer Attack Phases (Information Aggregations, Analysis and Interpretation, Armament, and Influencing) have a fully mediate and significant impact on improving the security countermeasures by Social-Engineer Involvement. The findings of this study help to provide deep insight to help security professionals prepare better and implement the right and appropriate countermeasures, whether technical or soft measures.