Sorry I came up blank searching on this, although it is probably one of those "duh" items.
On all of my other ppc phones, I could pre-program a series of digits, symbols and pauses that I launched after the initial number answered (i.e for checking voice mails, etc). On my last phone (700wx), it was done by editing a speed dial entry, as I recall. I don't see anything like this on my Mogul.
Be gentle, its Sunday...