Okay, calling a phone number isn't the most ground-breaking thing Siri on your iPhone 4S can do, but you'll find Siri is a lot more accurate at the task. How many times have you said into an old phone "Call home" and your phone replies with "Calling Dr. Lome." Sigh.
As with all other Siri tasks, all you have to do is ask Siri to perform a task, and she will comply.
Press and hold the Home button.
Wait for the short chime and then give Siri the command.
For example, you can say "Call" and give the person's name.
As long as the person is in your Contacts, Siri will call the person for you.
If you have multiple phone numbers for an individual, Siri might not know which phone number to use. That’s why she may (politely) ask for a bit of clarification.
If you know that a contact listing has multiple phone numbers, you can go ahead and specify which number to dial, like this:
Press and hold the Home button.
Begin talking after the short chime.
You could say "Call [person's name] mobile." Or "Call [person's name] home." Or "Call [person's name] work."
You get the idea. Siri knows which number to call because you're more specific.
Specify which telephone number Siri should dial.
You can tell Siri who the important people are in your life — such as "husband," "mom," or "brother" — and Siri remembers. For instance, after you tell Siri your wife's name and Siri associates "wife" with the appropriate Contacts listing, you can tell Siri to "Call my wife on her work phone," and the task will be performed. You can also specify your home and office numbers for Siri; after doing that, you can say things like, "Call home."
If you want to call a phone number that's not in your Contacts, you can do it by saying the 10-digit number verbally:
Press and hold the Home button.
Tell Siri what you'd like, but wait for the familiar chime first.
You can say "Call" and give the phone number. Or say "Dial" and give the phone number.
Siri dials the number for you right away, of course.