pass data from external php form ?

[ghost0001]

Here is the problem , I have a cgi based shopping cart , I have a required field that is for an area code and telephone prefix . My upstream provider will only provide a php form ( on his site ) with the area code / prefix selections
here :
[a href=\"http://www.inphonex.com/secure/choose-did.php\" target=\"_blank\"]http://www.inphonex.com/secure/choose-did.php[/a]

Is it possible for me to "pull" the user's selection from that form and pass the data into the correct field in my html / cgi form ?

What if i rewrote my form into a php form would it be possible then ?

I know the much simpler answer would be for my provider to give me the selections as a csv and let me code it into my site , but because this changes constantly they won't provide it and they see it as a security risk to give me direct access to the MySql database .
Therefore I am trying to find a reasonable work around