This document explains why IPSEC VPN clients don't work on Verizon 4g network.
The Cisco IPSEC VPN client is able to connect to VPN gateways without any issues over the Verizon 4g network. However once connected, the client is not able to pass any traffic at all. The counters on the client indicate that the client is encrypting data however, there are no increments to the decrypt counters. This issue is seen on the entire gamut of windows OSs. One of the deal breakers with the new Verizon 4g network is that the new LG VL600 and Pantech UML290 run a privately routed IP (10.) address that ONLY allows outbound traffic - no inbound traffic can be passed through. This means that if you have a need for remote access to a device, Verizon's new 3G/4G-capable devices will not allow you to access them like you could with a 3G-only modem.
Based on suggestions made by Verizons it seems as though the following things need to be attempted:
1. enable Nat-T. For more information regarding nat-traversal please refer to the following documents: