The problem with SIP on the DIR-825 A & B is that the SIP ALG firewall does not take into account port 5060 used my many VoIP service providers. To fix this, check the logs for outbound ports that are being blocked by the SIP ALG firewall. Go to Advanced, Application rules and add a rule, ie Voip for UDP port 5060, trigger and firewall, this will stop the port 5060 outbound blocked messages in the log.
Next assign the Voip TA a DHCP IP reservation under Setup, Network Settings then add the now static DHCP IP address to Advanced, QOS rules and only give that IP address, ie 192.168.0.199 thru 192.168.0.199 a Priority of 1, "Any" Protocol, ports 0 thru 65535. I recommend changing the VoIP TA IP address to 192.168.0.100, leaving the DHCP leased / expires in the 170 to 190 range. ie, what IP you assign on the router the TA will pick up based on mac address. Leave the Remote IP Range 0.0.0.0 thru 255.255.255.255. You must place the VoIP TA in the DHCP reservation list because the QOS Rules will not follow a DHCP IP lease expiration if your TA is assigned a new IP address by the router.
Limited to a number of SIP applications this router recognizes automatically, ie Skype, AIM Talk, Calista, ICQ, Pal Talk - all PC based applications, D-Link engineers did not take into account firewall settings for physical TA's like Vonage, ITPVoIP, and others. Your VoIP TA and service provider may be slightly different, but you get the idea how to use Status, Logs and Advanced, Application rules to open blocked outbound ports and use QOS firewall settings to prioritize VoIP traffic. If you follow this setup you will also eliminate the "Blocked outgoing ICMP packet (ICMP type 3)" message in logs.