If I understood your question correctly, you want to call a Parent Page method from IFrame in the same page.
YES you can
.
Let say you have below Structure
[mainpage markup]
[main page JS ]
function TestMethod()
{
}
[main page JS ]
[iframe id="myiframe"]
[/iframe]
[mainpage markup]
Then you can call the
TestMethod
as below
document.getElementById('myiframe').contentWindow.TestMethod();
contentWindow will return you parent container. Hope this helps !!