Can an application subscribe to System level event like Phone_Call_Coming or Timer

I understand that, Windows Phone 7 wont let me run an application in the background, thats fine for battery issues. Ok, Push Notification is there for letting my server trigger an application, thats nicer, but, there are many scenarios where my server wont be able to know some events of the phone. For example, I want to create an application which will be fired as soon as an incoming call is coming. My application will answer the phone call and play my custom mp3 player to the caller and do some fun or some business tasks. I can do this using Windows Mobile 6, but Alas, I dont find any way to do it in Windows Phone 7. Obviously, my server wont know when an incoming call is coming so Push Notification wont be a solution. One solution could be something like, System Level event. I mean, an application can subscribe to a system event like Phone_Call_Coming. When this event is fired, my application will be poped up with the argument (phone number who is calling) passed to my application. Is not that possible at all ? Also, I need to create my own Alarm clock in my own way. My alarm clock will play my preferred mp3 file, so I need to keep my app running all the time as service. But Windows Phone 7 wont let an app working as a service for power issue and intercept / dial phone call for security issue. Well, MS could let the user define trust level for the app. Minimum trust, Full Trust etc. So, if the user has doubt, he/she could set minimum trust so that the app wont be able to make any phone call by itself. I would love to let my application dial a phone number without user's intereption which can be a FULL Trust feature. Whoever wont trust my application wont let my app install in FULL TRUST. Simple and Straight forward, is not it ? I want to develop application just for me, not for other users, so, for me, I could use Full Trust and enjoy my own built apps. Looks like, I need to stick to Windows Mobile 6 anyway. Please help me with a guideline.

You can't intercept phone calls or react to any system events. What you want to do isn't possible with Windows Phone 7. You'll have to try other phone operating systems like 6.5, iPhone or Android.

Feel free to make a suggestion for the WP7 platform in this regard in the suggestions forum. There has been a fair amount of interest in this requirement. Keep in mind this is effectively a v1 product.