Iphone dialing. A basic phone allows number manipulation to add a prefix on a stored number in contacts, is there a way to do that?

Question

Iphone dialing. A basic phone allows number manipulation to add a prefix on a stored number in contacts, is there a way to do that?
This is specially useful while traveling and you need to use numbers stored in a domestic style. Adding the possibility to have a prompt or cursor in the number dialing screen would be very helpful

Answer 1

Further to my question Ill add an example:
I'm in the US and need to call to Mexico City, the way to do,it is [phone]. This number is stored (and has been stored for years in yahoo contacts) as 12345678, the way you dial it locally; so now in order to call I need to add +5255 as a prefix to my stored contact.
This is extremely easy in other simple phones and smartphones like Blackberry by copying, pasting and editing the final number you need but it seems impossible on iPhone. It requires a great deal of manual copying.
I travel a lot and would be very thankful for a solution