Redirection to a landing page with low/no credit for NCC

 Hi,  Could somebody make a suggestion for how I could implement a system to tell a GGSN to redirect to a website for informing a user that their credit has run out, when the credit has been exhausted on the charging system for NCC.  The GGSN can redirect to the web site, but currently there does not seem to be any provision to perform this using the Diameter CCA message, unless I'm mistaken,

Thanks,

Paul