Internal intranet site to Sharepoint outside access

hi all

We have sharepoint 2010 and it is the enterprise edition installed on WIndows 2008 R2 Enterprise.

My question. I have an application server that hosts many IIS websites which we can access Internally within our network. I have this SharePoint 2010 that is facing the internet and is accessible for all users who have an Active directory account. I want to have these internal website accessible inside SharePoint, is this possible. ?

I have done a Page viewer webpart and mapped the websites. It works internally but outside the company network it wont and says page cannot be displayed.

I need the basic configuration and will pick it from there further on or is it something that I am doing wrong?

Any help is appreciated and thanks.

regards

Jo