Is there a way to connect a Mobile phone to a Modem?

very few phones support this, although it is a growing trend. while you can't use dial up, some phones can support a CDMA modem connection. otherwise purchase a program called laplink (it comes in a box that should also contain cables to hook your computer to your phone.
what kind of phone do you have?
who is the service provider?

Do you want to
1. use the mobile phone to surf the internet
Most new phones have internet access now, they come with WAP and/or GPRS. Your phone would need the software to browse if you wanted to use the net.

or

2. use your laptop to surf and the mobile phone as a modem?
I have seen cards that you can buy or depending on whether bluetooth is available and what services it has, you could pair and use as a modem. Some more info available here http://mobileoffice.about.com/od/usingyo...