Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE Students ( cell_mobile_number VARCHAR, student_id VARCHAR )
TABLE: CREATE TABLE Student_Addresses ( student_id VARCHAR, monthly_rental VARCHAR )

### Question ###
What is the cell phone number of the student whose address has the lowest monthly rental?

### Accurate SQL ###

SELECT T2.cell_mobile_number FROM Student_Addresses AS T1 JOIN Students AS T2 ON T1.student_id = T2.student_id ORDER BY T1.monthly_rental LIMIT 1