Side By Side Comparison of Karbonn KT21 and MTS Mtag 3.1. Compare Processor, display, RAM, Storage and other features here. You can quickly compare Karbonn KT21 and MTS Mtag 3.1 smartphones just by looking at their ratings and results showing "winner" and "runner up." There is also a short analysis comparing different features of Karbonn KT21 and . You can also look at each hardware feature individually to perform your analysis while comparing mobile phones.