HOX+ Signal loss at high battery levels

My problem:
I get permanent loss of signal which can only be regained with a reboot or turning airplane mode of an on again. This problem seems to be related to battery levels.
When charging: full signal

100%-90% battery: signal lost on standby every 5 mins

90%-80% battery: less frequent signal loss

80%-50% battery: signal loss every half hour or so

>50% battery : No signal loss

Issue happens regardless or what ROM, kernel or any other mod. Happens on stock too. Signal loss only occurs on standby. Sync settings, HTC sync, fastboot and network configs have been changed but again I've had no luck.
Could this be a hardware issue related to the battery voltage?

INFO
Radio: 3.1204.171.33
Boot version: 1.72
Rocovery: TWRP (viperx+)
ROM: Viperx+ 2.2
S-off and unlocked

grigoriisi said:

are sure your sim is ok? try putting some clear tape on the plastic part of it . that will make it thicker and contact will be better. just a suggestion.

Click to expand...

Click to collapse

That's not the case. Every time the rate of signal loss is proportional to the battery level. Also the signal loss occurs ONLY on standby. I highly doubt it's the sim but thanks anyway. Also to clarify I have taken apart the phone and all the contact connections have been adjusted so it always connects. I have a sneaking suspicions it's the radio module being fussy with the voltages.

I can confirm that this is a hardware fault. regardless of was OS is installed on it, the same pattern occurs. Furthermore I'm uncertain about the warranty, not only because I unlocked it but also when I set up the phone, I get a warning saying this phone is a "test device" No doubt this was a showroom/pre release version hence the fault in the first place. Are there any hardware fixes available aside from raising the connectors that contact the rear panel.
As the phone never looses signal when plugged into anything, would buying an external battery pack solve the issue? I know they use the docking points on the back of the phone but I don't want to sink money into this when it could be a waste of time.
Thank you in advance.

*UPDATE*
according to this thread, the pins at the rear of the phone are attached to the charging port
http://xdaforums.com/showthread.php?t=1611116

So in theory if I buy a battery pack, it will mimic charging right? Thus this should solve the signal issue?
Turn out my pogo pins are doing f*** all. the new backup battery pack doesn't charge the phone, even when the phone's battery is dead! I'm out of options now (unless someone happens to be selling their HOX/HOX+)