I am using cisco 857w router just for SIP based IP phones. The router seems to be a SIP aware router. It shows the public IP address in the SIP contact header thus breaking the NAT traversal. Also its seems like it is not using available bandwidth of the DSL as if the multiple phones are on the call the other ones suffer one way speech problems. Can someone help me to disable SIP ALG on the router? .Currently no firewall has been setup yet.