When I frequently make calls to automated systems that require an additional digit or extension to be dialed, I like to add these dialing key presses into my contact’s number with dialing pauses as appropriate. The iPhone makes it easy to put pauses into a contact’s phone number.
When editing a contact’s phone number and you are ready to insert a pause, tap the + * # key at the lower left of the screen as shown with a red asterisk in the image below:
After you tap this key, the keyboard layout will change to this:
To insert a pause, simply tap the Pause key. After you tap this key, the keyboard will revert to the normal layout. If you didn’t mean to insert a pause (or pound or asterisk), tap the same lower left key (which now will show 1 2 3 to return to the numeric keyboard.
The phone number displayed on the screen will show a comma where a pause has been inserted. For longer delays you can insert more pauses.