Short　Message　Service　(SMS)　is　a　text　messaging　service　component　of　smart　phones,　web,　or　mobile　communication　systems　which　requires　a　high　level　of　security　to　provide　user　authentication　and　data　confidentiality.　To　provide　such　security　features,　a　high　security　communication　protocol　for　SMS,　called　Message　Security　Communication　Protocol　(MSCP)　was　proposed.　In　this　paper,　MSCP　is　formally　analyzed　using　an　automated　logic-based　verification　tool　with　attack　detection　capabilities.　The　performed　formal　verification　reveals　that　the　proposed　protocol　is　susceptible　to　parallel　session　and　denial-of-service　(DoS)　attacks.　The　reasoning　why　these　attacks　are　possible　is　detailed　and　an　amended　protocol　is　proposed　to　counter　the　identified　attacks.　Formal　verification　of　the　amended　protocol　provides　confidence　regarding　the　correctness　and　effectiveness　of　the　proposed　modifications.　©　2018　IEEE.