redirect refresh vs redirect location

[eluser]searain[/eluser]
url helper, redirect does a "header redirect" to the local URI specified.

What redirect('/login/form/', 'refresh') actually doing in the background?

Does it do a header refresh, something like

header( "refresh:0;url=wherever.php" );

According to the manual, "The optional second parameter allows you to choose between the "location" method (default) or the "refresh" method. Location is faster, but on Windows servers it can sometimes be a problem."

So it seems 'refresh' has less problem than 'location', but my mobile site support old blackberry, like blackberry 4. and redirect('/login/form/', 'refresh') has problem, cannot redirect, but redirect('/login/form/', 'location') is fine.

refresh header is not a standard http header, could that be the root of problem?

Thanks!