In my experience (recent experience), Linksys and SIP don't mix. At least not yet anyway. I've had some bad experiences with newer Linksys routers. It's possible it is specific to my application, but reading some reviews on various websites, I am not alone in the troubles I had. Do your homework before buying. You usually can't go wrong buying the Cisco products. They are stable and do what they were designed to do. My recent experience shows that Linksys makes claims they can't live up to (marketing hype), and the Cisco name on the Linksys router means NOTHING in regards to quality. Also, if you have some means for Cisco support, whether direct or indirect, you will have far better results and get much more help than trying to get support from Linksys and their level 1 techs.

Okay, now I'm wondering...what do you mean by "SIP-aware"?