Learning in the cellular phone environment enables utilizing the multiple functions of the cellular phone, such as mobility, availability, interactivity, verbal and voice communication, taking pictures or recording audio and video, measuring time and transferring information. These functions together with mathematics-designated cellular phone applications facilitate authentic learning based on real-life phenomena, and widen the range of mathematical activities possible to carry out. This research shows that the cellular phone provides the mathematics students with rich, diverse and colourful learning environment in and out of the classroom. The participating students worked with the cellular phone to carry out activities involving formal mathematical phenomena and at the same time authentic real-life phenomena which they modelled mathematically. Doing so, they worked individually and collaboratively with diverse, specific and general mathematical concepts and at the same time practiced specific and general mathematical procedures, which expanded their mathematical knowledge and meta-knowledge. The cellular phone enabled the students to work with various representations of mathematical objects which encouraged them to investigate these objects independently or with the guidance of their teacher. The students also could tackle advanced mathematical objects intuitively based on their visual representation and actual realization in real-life situations.