GATE

Yes, candidates can get admission to ICT M.Tech course without GATE. Candidates can also opt for other entrance exam option, such as GPAT or GAT-B exams. Further, some ME/ MTech/ M.Chem.Engg. specialisations, an institute-level written test, and an interview is conducted along with due consideration to the exam scores for final selection. Its is mandatory for students to have completed bachelor's degree with at least 60% aggregate or equivalent CGPA (55% aggregate or equivalent CGPA for the backward class candidates). 

Candidates applying for M.Tech at Indo Global Group of Colleges require having a valid GATE score. However, it is not mandatory. Candidates with insufficient GATE score are also offered admission in M.Tech based on their merit. In such a case, the selection of the aspirants is based on their inter-se-merit in qualifying examination. Besides, aspirants must also fulfill the eligibility requirements for admission.

No it is not all mandatory to take a joint M.Sc PhD after qualifying for IIT JAM. Although many students choose this, you can just apply for M.Sc now and if you feel apply for PhD later.

For GATE also the similar thing is followed.