Nortel Contivity VPN Client with cisco 2612/2611 router

Im facing problem with configure my router. i have cisco 2611 and 2612 router. Im using Nortel Contivity VPN Client. when i try to connect thru cisco so it doesn’t connect and when i connect thru DSL so it connected. we have two offices one in UK and one in Pakistan. In Uk office using Nortel router. So pls somebody tell me how can i configure it and connect it. thanks.