Here is another VPN issue i have noticed:
I connected an SR520 to a UC520 with a standard site-to-site VPN crypto-map. I put a 524SG phone at the remote site, and it would not register to the UC520. I then replaced the crypto map configuration with an IPSec Tunnel configuration, and it fired right up. Any idea why the cryptomap setup didnt work with the 524SG phone? I have noticed this twice now. I have either used an ipsec tunnel or a DMVPN config to fix it. My configs are 'standard' and fairly simple, and all other traffic is fine. So it has to be something voip specific that I am missing. I am using routemaps to deny NAT/PAT, specifying the correct interesting traffic, everything i can think of is fine. I have setup tons of VPNs.
I ask because now I am having an issue at another site, with Panasonic VOIP phones and Cisco 871 routers. There is a crypto map ipsec vpn between two sites, all traffic flows ok, but there is no audio when a call connects on the phones. Am I missing something in my crypto map configs that would relate to voip connections getting lost?