It's been a while since I VPN'd on a Mac...
The modem type/make won't make a difference. As long as it can establish an internet connection, you're fine. What makes or breaks it is the VPN client on the Mac. Last time I did this I was using a Cisco firewall which had Mac VPN software as well, and all worked fine. Nortel also used to publish a Mac VPN client that was used on other brands.
At one point, OSX used to come with it's own VPN client you could configure to use with your VPN. I never tried it, nor do I know if it still ships with Leopard or Tiger.
I currently drag my PC laptop home when I need to VPN into work only 'cuz I'm too lazy to figure out the Mac issue. One day...
The modem type/make won't make a difference. As long as it can establish an internet connection, you're fine. What makes or breaks it is the VPN client on the Mac. Last time I did this I was using a Cisco firewall which had Mac VPN software as well, and all worked fine. Nortel also used to publish a Mac VPN client that was used on other brands.
At one point, OSX used to come with it's own VPN client you could configure to use with your VPN. I never tried it, nor do I know if it still ships with Leopard or Tiger.
I currently drag my PC laptop home when I need to VPN into work only 'cuz I'm too lazy to figure out the Mac issue. One day...