Welcome to the world of iPhone! I'm sure that you will love your new device. There are many great features that the iPhone provides. If you would like to setup a certain mobile number for easy access then there are two options that can be used for the iPhone.
Option 1:Favorites can be setup on the device for easy dialing.
Option 2: Download a speed dial app.
To setup Favorites on the device simply touch the Phone icon and touch Favorites in the lower left on the screen. Once on the Favorites screen, simply touch the + in the top right corner to add a contact number to the Favorites screen. If you prefer an app for easy speed dial access then you can search speed dial in the app store. Even though I am unable to recommend an app, the reviews that's posted for each app is a great resource in helping you decide on which app best suits your needs. If you have any additional questions or concerns then don't hesitate to respond to this posting for help.