User interface and minimal functionality as per requirement.

I think one can give various answers depending on the 
requirement of the testing being done:

Some of the basic mobile testing header level scenarios are:

1) Battery charging scenarios
   a) Fully charging and launching the application
   b) operating mobile with charger on

2) Launch of application: Power on/off and Stand-by modes, 
if any

3) Basic Menu functionality checks:

    EX: a) Messages
              i) Inbox
             ii) Outbox...

        b) Camera
        c) Mail

4) Mobile operation: With and without SIM card

and so on...hope one gets the idea..

Cheers,
sb

Mobile testing for an application has following parameters
to Consider.

 1>Is there any prerequisite for our application to run.

 2>Installing an application on Device or external memory
card makes a difference or not?.The functionality of the
application on the mobile should remain the same.

 3>Have many applications running at the same time and then
check the performance of the application.

 4>Opening the application from a shortcut or from running
programms should open up fine.

 5>Check the application UI w.r.t native phone U.I

 6>The application should not interfere in phones basic
functionality which can disturb the user.

 7>Mobile tetsing is done keeping User's expectations in
mind to make it as user freindly as possible.

 8>The terms and captions used in the Application should be
self explanatory as far as possbile .

 9>There should be a "HELP" file provided to a user along
with the application to use on the mobile.

 10>Use your intelligence and smartness to figure out
different possible scenarios that may Crash the application
running on the mobile phone.

     There can be many such points please add If you have one.