Q on VoIPo SIP outbound vs. router

[stevech]

Trying this question here before I file a trouble ticket...
My router's event log (syslog stored internally), has several per minute notices. Each says the router blocked a SIP packet from the Grandstream ATA directed to server 72.51.46.124:5060. This is OUTBOUND.

My router has firewall settings for SIP/ALG and this is enabled. I assume this is for inbound SIP connections (receiving a call).

The firewall settings in the router do not have anything specific on blocking ports for OUTBOUND.

Port-forwarding for inbound seems N/A for this discussion, but it's enabled none the less, to forward to the ATA.

The exact router message is "SIP ALG rejected packet from 192.168.1.51:5079 to 72.51.46.124:5060" (where .51 is the Grandstream on the LAN) All log messages have the same destination SIP server IP.

which suggests that the ALG in the router decided the SIP packet is invalid and should not be forwarded to the Internet?

I also tried putting the ATA in the router's DMZ. No help.

All this does is quickly fill up my router's log. It may also be a problem when the ATA tries to contact a designated SIP server for registration, but I have no loss of service problems for registration.