Help needed with Comcast SMTP change

I need some help to change the SMTP port which is blocked by Comcast. I was using port number 25. It is not blocked and the mail service is not working. I cannot send any mail from SBS 2003. I am not able to find any information on how modify the port for smtp. I am trying to look some settings and the ISP is not helping me out. I am trying to do that manually but it looks that the issue lies on the isp end also. What are the ways available that can provide me information on what all ports are open.

Yes you can do that from SBS only. It happens a number of time for security reason the ISP blocks the port and due to which some of the services stops working. I am giving a link below that has detailed information and steps to modify the port settings. It is necessary that the ISP must first inform about port blocking and later on it must be applied so that the user can get time for changing the settings.

How to change SMTP port 25 to another port in Microsoft Exchange Server

Did you tried to contact the isp and ask them to unblock the same. Actually it not tough to change the port but sometime modified settings does not work. So the easy to fix the same is to first ask for modifying the port and using the default one which was configured before. And then checking back if everything is restored or not. There are ample of ports available that you can use. But you will need to ensure that security applications do not block it.