Yes, there is internal sliding in NIT Calicut. For the M.Tech course, students get the chance for internal sliding during or before the college spot round. For the B.Tech course, usually, the students are given a chance for internal sliding after their first year.
However, there are conditions to change your branch from one to another at NIT Calicut –
Contact your program coordinator to know the details of internal sliding at NIT Calicut. I hope this answered your question.