HG659 and HG659b hacks and tweaks

We have a couple of ISP specific HG659 threads

VF - http://www.geekzone.co.nz/forums.asp?forumid=40&topicid=195795

VF - http://www.geekzone.co.nz/forums.asp?forumid=40&topicid=208229

BigPipe - http://www.geekzone.co.nz/forums.asp?forumid=158&topicid=201985

L2TP on HG659 - http://www.geekzone.co.nz/forums.asp?forumid=66&topicid=208369

There also appears to be a thread on the OpenWRT forum

https://forum.openwrt.org/viewtopic.php?id=54817

I'm personally interested in any hack/tweaks including

Cross flashing firmwares

BP / Spark / Vodafone firmwares appear to be interchangeable - but double check your hardware version

Shell Access - See BigPipe Thread

Using as an additional AP

Using as a VOIP device

Bridge mode - just operating as a VDSL modem

OpenWRT support

My ideal would be OpenWRT or LEDE support but I have a feeling that would break the VOIP support.

I'm currently running a device as an AP with DNS/DHCP turned off and connection via LAN Port.

BigPipe Firmware

Telnet access with Shell

Lack of a default route means I can't test VOIP support. Anyone else found a guide on setting a default route to match my existing firewall?

Tried on the command line, but it appears you can't drop a full root shell which restricts some of the commands when on the telnet console.