Mobile Phone Functional Testing Tool

You will need to download and install the SDK for each platform you wish to write for.  Each SDK should also have a device emulator that you can use to install, and test the application you're writing (or at least I know windows mobile and android do).  For windows mobile apps, it's best to use visual studio and you can use any of the languages in it (C#, vb.net, etc).  For google android, there's an sdk and directions for using eclipse as your IDE and it uses java for it's platform.  Good luck.

Thanks for the reply.  I have another queries.

 What about AT commands?  
Do all Mobile  phones have AT Commands?  Can I use AT commands for my Functional Testing Tool?
Or is it better to go with the SDKs?

Like, as you said with WindowsMobile, do I have to use SmartDevice project or I can use other project of Visual Studio as with only smartdevice project i can find reference and with other project  i cannot find such references. By using all these things, it requires application to be deployed on mobile phone and then will perform testing right.  But, is there any other way like i do not have to deploy application on Mobile, i can connect to the device and  my application will check all these stuff and give me the response accordingly?

There are SDKs for Android, Symbian etc.  But Android is based on JAVA and Symbian is all C++.  Is there any way , I can use such SDKs with C# or I have to go with the same platefroms?

I don't know about the AT commands.  I've never attempted their use.  I've only ever used SDK's.
In my visual studio, when I select to create a new project, I see templates for smartdevice under visual basic, Visual c#,  and visual c++. A project could be created using any of these templates.  The testing can be performed on a device emulator, which is part of the sdk and integrates with visual studio.  The emulator shows the graphics of a phone of your choice on the desktop that loads and runs the desired windows mobile platform.  You application will install into the emulator and you can run and test (even in debug mode with visual studio interaction) as needed.
I can't answer for Symbian, but I'm pretty sure you won't be able to write with C#, because the .net api's are not installed on the android devices.  (I don't think google wants to support MS too much  :)  )  Good Luck!

Thanks for SmartDevice Project explanation.  I alreday tried and its fine with emulator.  Now I need to check physical device. How will I do it?
 I have one mobile with WindowsMobile 6.5 OS.  But, I am not able to find plateform as WindowsMobile 6.5.  It gives emulator for 6.5 but not all.
How to identify which emulator we need to select? Could you please guide me?
After testing with emulator, I need to check with Professional device also , Could you please tell me the procedure?

I am happy to receive many replies for my question.  They helped me to understand many points.  But for my queries like if I go for SmartDevice project i can test with  emulator but the same thing if i want to test on physical device how to do it? I did not receive any specific reply for that.
Your answer suggested me to use eclipse for android.  I am a .net developer and working on C#.
I want to use C# only. My query is can I use C# for all these stuff?   Could you please answer my queries?

I received useful information from you.  But still my application is under development.  So I leave this question open.  

This question has been answered.  If you have additional question, open new ones.

The answers help me to take you in a proper direction.  But, its not what I am looking for.  Thanks.