Qos - with ipsec vpn tunnel

Hi,
we have an 9.x sw appliance with 2x ipsec vpn tunnels configured to our remote branches.
In one remote branch we have a PBX connected through a sip trunk to the main office pbx.
We have an ADSL connection (20 down, 2 up).
We plan to change this link to a HDSL simmetric line but until then I need to priorize the voip and vpn traffic because the uplink bandwith is heavily used.
I read the manual and it's clear how to configure qos (1-define interface download/upload setting, 2-define traffic selectors and 3-define bandwith pools) but I did not understand if:

1) is it possible to priorize the sip traffic INSIDE the vpn tunnel?
2) is it possible to priorize the entire vpn tunnel that transport the sip traffic VS the one that do not have it?

Thanks for your help.