Student response systems (SRSs) have increased in popularity over the past decade, with their use in the classroom steadily increasing. They offer several important pedagogical benefits including improved student learning, increased student interaction, improved student attendance, better student satisfaction and the creation of an enjoyable learning atmosphere. Most notably, they provide a mechanism for anonymous submission, thus allowing students to respond without the fear of being identified. While several different types of such systems exist, most of them have several drawbacks associated with them. These include (i) limited input capabilities, as the SRSs typically only offer a multiple-choice option and/or a numerical and textual based submission, (ii) practical issues in terms of portability, as the lecturer is typically responsible for having to carry a large number of devices to the classroom, and (iii) lack of suitability for distributed classrooms, as most SRSs employ short range infra-red communication that restricts their use to the physical classroom. In this paper, we propose the use of a smart phone based student response system that overcomes these issues. This new system builds upon existing work by the authors, whereby a tablet-based system was developed for in-class use. This paper has two key aspects - the first relates to modifications to the existing tablet-based solution and the second is the evaluation of the new system in a distributed classroom setting. Details of the modifications and the results of the evaluation are both presented within.