Conference Calls on the iPhone

I was wondering how you can make conference calls on the iPhone and found the following instructions on the WEB.

The iPhone lets you merge up to five calls at a time to turn them into a conference call. Making a conference call on your iPhone may be easier than getting those same five people in a room at the same time.
Start by making a call and then placing the caller on hold. Tap Add Call to make another call and then Merge Calls to bring everybody together. Repeat this exercise to add the other calls.
Here are some other conference call tidbits:

• iPhone is actually a two-line phone, and one of the available lines can be involved in a conference call.
• If you want to drop a call from a conference, tap Conference and then tap the red circle with the little picture of the phone in it that appears next to the call. Tap End Call to make that caller go bye-bye.
• You can speak privately (one-on-one) with one of the callers in a conference. Tap Conference, and then tap Private next to the caller you want to go hush-hush with. Tap Merge Calls to bring the caller back into the Conference so everyone can hear him or her.
• You can add a new incoming caller to an existing conference call by tapping Hold Call + Answer followed by Merge Calls.