Which table does the Phone module store data in? I have installed the Phone module to create a field to take input data as mobile number.

I would like to fetch the mobile number back from database to be displayed in a block. I am not getting the table in which the phone number is stored. So in which table is the phone number data is stored?
If this module defines a field, then the table is named after that field. So if your field is called field_phone, the table is called "field_data_field_phone". However, getting the value direct from the database is not the right "Drupal way" to do it. 

You say you want to display the phone number in a block, but I assume this is within a specific context, such as on a page for a node or user. One way to do this would be to use the Views module to define a block with whatever fields you wish to display, using a contextual filter to get the node or user ID from the page arguments. 

But more information is needed in order to say whether this is the right answer or not.