I would really value some advice regarding a Cisco ACL policy design. I am a Voice engineer and I have setup an Asterisk High Availability cluster and I have a Cisco 1841 controlling the LAN/WAN access to this cluster.
I have quite a few clients who will be using this cluster for hosted telephony and they all have fixed IP addresses that I can add to the cisco ACL and allow full access to their SIP/IAX phones for registration.
Here is the problem:
Some of my clients have home connections and their routers have dynamic IP's so I can't open the IP for access to them as their IP may change. I also have clients that have SIP clients on their mobile phones and we have a similar problem with these.
I can't run a mac-address filter on the router as it is a layer 3 device and the only option that I could see is maybe an ipSEC or PTPP.
Does anyone have any sugestions?