EXECEUTE AS CALLER

I am trying to assign execute permissions to users on a stored proc. The users do not have read permissions on the tables called inside the SP. When i read the MSDN site about EXECUTE AS CALLER option, it says...
"...The user executing the module must have appropriate permissions not only on the module itself, but also on any database objects that are referenced by the module."

does this mean the users who are executing the procedure must have access to all the underlying tables inside the SP?

Thanks Luis.
I did a check with sample table...
I created a stored proc AccessTestTable that does a select to the table TestTable. I created a Testuser and granted exec permission to proc AccessTestTable. Even though the Testuser did not have select permission on the table (he could not do a select * from table outside the proc), he can access the table via the stored proc.

Please explain me why is this so...

Code samples...

-- Create Scripts

CREATE LOGINTestuserWITHPASSWORD='abcde#123'

CREATE USERTestuserFROMLOGIN Testuser

CREATEPROCEDURE

AccessTestTable

WITH

EXECUTEAS

CALLER
AS

SELECT

SUSER_SNAME

()

SELECT

TOP 10 *FROM

TestTable

GRANT EXECUTEONAccessTestTableto Testuser

EXECUTE

ASUSER=

'SQLUser1'

SELECT *FROM TestTable -- This query throws error

EXECUTE AccessTestTable -- This returns values from the table without error

I am confused.
In my example, the user does not have access to the objects, but executing the SP with his privileges (EXECUTE AS CALLER) and still, he can run the proc without errors. I see this as a conflict with what MSDN says.

The user is SQL Authenticated DB user

looks weird for me too...
So, I created this account on my server to test. I have attached the scripts above too...