This is not a full answer but more of a caution statement. In my experience, it can be very difficult to build a VPN between a Cisco and non-Cisco devices. Cisco may have the standard phase 1 and phase 2 negotiations but the priorities may differ and parameters may not match as expected. You are usually better off having the same VPN devices at both ends if possible. You should find a technical document from the equipment vendor for the non-Cisco device as that is likely to be your best option of getting a solution to this issue. You may also need technical support from either Cisco or the other equipment provider to resolve any issues required.