Dial SIP support for RFC 4240 / NETANN?

I try with Asterisk (1.4) to Dial to a external SIP platform with required the NETANN syntax (rfc 4240):

          exten => _X.,n,Dial(SIP/ccxml@hostname:5060;ccxml=http:/website/document.ccxml)

which should issue the following SIP request:

          INVITE sip:ccxml@hostname:5060;ccxml=http:/website/document.ccxml

but I get instead:

          INVITE sip:ccxml@hostname:5060 

without the parameter field. These is a way to configure Asterisk to accept this syntax?

Thanks,
Sylvain

I’m pretty sure you have to change the source code. I don’t believe there is any way of adding parameters, or even feeding in a raw SIP URL.