asterisk users - Feb 2008 - is tos=ef same as tos=0xb8 same as DSCP ef ?

Trying to figure out how to prefer voip traffic on a dsl line.

Found a great howto:
http://www.howtoforge.com/voip_qos_traffic_shaping_iproute2_asterisk

but I'm trying to figure out the relationship between the tos of 
iax.conf and tos of tc from Iproute2. my traffic goes from my linux 
router to a CPE cisco box. I understand Cisco uses tos ( usually 
referred to as DSCP, just to keep us on our toes) ef or 0xb8.

So when I use tos=ef in *.conf, will the Cisco router see it as Cisco's 
"ef", DSCP=ef?

And, for extra credit, can I use tos 0xb8 in iproute2:
tc filter add dev eth1 protocol ip parent 1: prio 1 u32 match ip tos 
0xb8 0xff flowid 1:2

It looks to me that priomap only has 16 values, so anything over 0x10 
won't work.

Thanks

sean