Question

what is use of split calls and merge cell

Answer 1

You can combine two or more table cells located in the same row or column into a single cell. For example, you can merge several cells horizontally to create a table heading that spans several columns.
Splitting cells is the opposite of the Merge Cells operation. The Split Cellsfeature allows you to split cells into two or more cells

Answer 2

Answer:

When you have two UniVoIP App calls established, you can merge the calls into a three-way conference call by tapping the Merge button. The two calls are merged into a conference between you and the other two parties. If desired, you can Split the conference back into two separate calls.