Rather than assign numbers on the keypad to speed dial your favorite contacts, the iPhone has a visual contacts list. Create a contact in iOS 8 and mark it as a favorite to dial with just two taps from your home screen.
Create and Favorite Contacts
Open the Phone app to the Contacts tab and tap the + icon in the upper right corner to start a new contact.
Add your contact's name and any other information you want to include. Tap Add Phone and enter a phone number. To change the type of number -- home, work, etc. -- tap Home. The type of number doesn't affect how your iPhone dials, but the label helps you keep track of numbers if you add multiple phone numbers for one contact. Tap Done to finish creating the contact.
Select the contact you just created on your contacts list, scroll down and tap Add to Favorites. Pick a specific phone number to add to your favorites. To favorite additional numbers for the same person, tap Add to Favorites again.
To dial this number in the future, just open the Phone app to the Favorites tab and tap the person you want to call.
Create a Shortcut in Safari
As of iOS 8, Apple doesn't include a way to create shortcuts to contacts on your iPhone home screen, but with a workaround, you can add phone shortcuts to Safari's favorites.
Create a bookmark to any website in your Safari favorites. The site you bookmark makes no difference. Open your bookmarks, tap Edit and pick the newly created bookmark.
Rename the bookmark as you like and then delete the Web address. In its place, enter tel:// followed by a phone number -- no need to include parentheses or dashes.
Tap the new bookmark in your favorites to place a call. When you tap the shortcut, you'll see a small window displaying the number. Press Call to dial the number.