Automated software testing (AST) is method that helps in the testing process, by means of time and costs and therefore efficiency. It is however not fully automatic, as manual effort is needed prior to execution of these tests. AST has consequently some drawbacks. Worth to be mentioned are difficulties in execution of the tests and test coverage but the main problem is the maintenance of the test scripts, which is reasonably expensive. A newer approach in AST is Model-Based Testing (MBT) that should provide easier and less expensive script maintenance together with better test coverage. However, there are defect types, which cannot be prevented with this model either thus making the question at issue for this paper related to the most problematic phases in MBT, which account for the defects that show after implementation of the software. Interviews at Ericsson and Spotify (both testing their products with MBT) have shown that the companies have different approaches to MBT. Ericsson uses it simply to generate the test scripts for later offline execution while Spotify has an online approach. These approaches lead to different results since Ericsson does not involve MBT in the test execution phase. Besides the different approaches, it showed that MBT has its own weak points which might lead to defects such as right choice of the abstraction layer and the selection strategy for choosing the generated scripts.