If you have contacts where a pause is required in their complete phone number (maybe you need to wait for the phone to be entered before you punch in their extension), you can easily add pauses to phone numbers in the iPhone including numbers for saved contacts. To insert a pause, hit the "+*#" key (lower left) to convert the "7 8 9" keys to "+ * #". When you do this, the 0 key will now say "pause". You can add as many pauses as you need in succession so that enough time elapses before you start dialing numbers again.