Cisco VPN client connection using Aircard

I recently purchased an Sierra Wireless Aircard 875U through AT&T. I can connect to internet fine, but I’m unable to make a connection to our corportat network through the Cisco VPN client set up on my laptop. “Remote peer termination connection” error message is received.
Any help would be great – I’ve gone through AT&T help, Sierra help and company IT dept help.

Karen