Open and Distance Learning (ODL) plays an important role in providing education to the students of rural and remote areas. In ODL, learning feedback and assessment process of learners requires time and cost using classical communication techniques. Emerging technologies like Mobile Assessment (M-Assessment) has gained momentum because of its potential as a useful electronic assessment tool available on widely used mobile devices. The mobile phone usage in Pakistan over the last ten years has been increased incredibly but the potential of Short Messaging Service (SMS) technology in assessment activity has not been fully explored. This study focuses on mobile SMS usage for formative assessment in distance learning environment of Allama Iqbal Open University (AIOU). The key objective of this study was to investigate AIOU students' satisfaction about the technology acceptance model for M-Assessment. The software has been developed in open source programming language using SMS web-service on the backend to conduct mobile based quiz. The survey methodology applied to test the technology acceptance model for M-Assessment showed that the majority (87%) of the respondents are satisfied with this mobile assessment method. It was tested on 277 selected students of Intermediate, Bachelor and Master's level enrolled in English and Information Technology courses at AIOU. Around 90% of the respondents regarded it as one of the quickest assessment methods. It was recommended to use this software in the assessment of ODL students.