Declining a call in locked screen

My iPhone just rang and it was flashing a call I badly wanted to avoid. However, in the locked screen it just appears as slide to answer with no other options for me. Where is the decline button when I need one?

Ok, here's what I have figured out,

1. Press the sleep or power button once, that will silence the call (ends melody or vibration from the iPhone)
2. Press the sleep or power button twice, that will decline the call. The caller will find the call terminated on his or her end or diverted to voicemail if you are subscribed to the service.