(original post around 16 May 2007 - By pressing with my thumb on the microphone area of the handset, I was able to permanently (for the time being) eliminate the hum. So the phone is functional again.)

Also, FYI the firmware on my phone.soyo.com CS G668 unit corresponds to the PA168S.zip download from the http://www.palmmicro.com.cn/PA1688/edownloads.htm page. I opened my phone and found the main chip is a PA1688-PQ.

Findings:

1. The chip designation ending in Q doesn't mean you should use their PA168Q.zip download, but rather, perhaps the CS marking means to use PA168S.zip. This is confirmed by also trying the remaining V download which gets rejected by the phone.

2. I set my debug value to all in the Soyo GUI before attempting any firmware updates. This way theres a good chance it'll reject anything you transfer that is incompatible

3. For some reasons the transfer portion of the firmware process (firmware upload) was very slow and halting when passing through a local D-link router, DI-604. Much better to just connect your PC directly to the phone, as has been advised.

Finally, I decided to switch back to the SIP firmware because under IAX the phone would lock up during a basic call like an echo test, somewhere around minute 3, or minute 8, or minute 11. The IAX page has a section on nat which describes this a bit further I think, however this may be a firmware issue because I seem to have gotten the lock ups even through a direct wired connection to a test asterisk server (no hub, switch, or internet). This was with IAX firmware file pa168s_iax2_us_159006.bin

The SIP firmware pa168s_sip_us_159006.bin seems to be running 15+ minutes

(Asterisk servers 1.4.19 local, and 1.4.19.1 remote)

I sometimes get noise in just one direction and it shows up on an Asterisk echo test as a buzz. By powering down the phone for a couple days the problem goes away for a while, however as of late it seems to return again rather quickly. Is the phone more susceptible to electromagnetic interference than most? Is this almost always an issue with the AC adapter, perhaps having gone bad?

Surprisingly or not PCPhoneline sells the identical phone as VST1000. PCPhoneline does not publish a user manual for their phone, but ... just use the same procedure as explained in this thread for the Soyo G668 to unlock the VST1000 and you will see the full extent of the configuration options.

This should help with the configuration of various VOIP providers or Asterix PBX.

Does anybody know how to make this phones ring louder? It's so low, you can't hardly hear it if you're not near them. Besides the ringing sounds just like regular dial tone which can be confusing. I tried changing the ring tone but all the ones I've tried are quite bad (http://www.aredfox.com/edownloadsring.htm)

@kotl: I didn't need to telnet to my unit to reset it and IAX worked fine with Asterisk.

I'm happy there are people having no problem with it. By the way speakerphone mode is also very quiet. I wonder if there is anyway to make it louder too. ( my speakerphone volume is 31 already... )

This phone doesnt come with IAX protocol in shipped firmware. So you will see only SIP settings after you unlock.
Also after you flash it with IAX firmware phone doesn't work even that you can change IAX settings, it seems trying to connect but doesn't work. So you NEED to reset settings and preferably DIGITMAP to make it work.

I'm afraid the steps explained by kolt are not quite correct. There's no need to telnet you phone in step 3. So after setp 2, just follow bzly2000 method to unlock the hidden SIP/IAX2 advanced features.