There are reports that the new iPhone with Siri is really chewing up network resources. Apparently DOUBLING the data transferred, this has put a strain on a lot of service providers. If your have dropped calls or reduced service, this might be one of the reasons why.
http://www.zdnet.com/blog/london/apples-siri-8216doubles-iphone-4s-data-usage/2194
My local provider (SaskTel) has been under fire for not being able to keep up with the demands of smartphone usage and gave several managers the boot as a result.