I’ve worked with a few user’s of BBTrackr to fix the Tunnel Failed error.  If your on BIS you need to set your APN settings.

The  value for your network can be found here:
http://blackberryforums.pinstack.com/360-tcp_apn_wap_gateway_port_carrier.html

To configured the TCP settings in BlackBerry as follows:

menu => Options – Advanced Options - TCP and enter APN information per the link above.

I hope this helps!