Plugging in Headset Physically Disconnects Phone's Speaker
-Grandstream has indicated that firmware cannot route rings through the phone's speaker if you have headphones plugged into the back of the phone. This is apparently a hardware design limitation, and makes the headphone jack effectively useless for many users.
-Grandstream has indicated that new phones have revised hardware which resolves this problem!
-So, the question becomes:
Are there any brave souls with hardware know-how who can figure out a hack to work around this bug?
Perhaps we could list ideas and attempts here, or on a seperate wiki page.
    • NOTE: (Dec01/05) Upon invsitgation the hardware configuration is set so that the act of connecting the headphone physically disconnects the speaker and microphone there is NO way around this without a new hardware revision, hardware hacking, or using a third party headset( one that connects inline with the handset and has a manual button) - SoloFlyer
    • NOTE: (Dec04/05) Completely disconnect 3.5mm socket for headset from back of pcb, get a push button (of the kind click on click off) splice this into the output for the handset, and into the onhook detection for the handset, drill a hole into the casing of the grandstream your done... you then have handset, speaker, and headset functionality... its is a little more complicated than this... :-/ - SoloFlyer

(use it on your own risk and be aware you lose your warranty !

From left to right I soldered on a wire to each red marked soldering point. Red, Blue, Orange White. Red/Blue are for the MIC, Orange/White are for the speaker. You could simply join red and blue, then join orange and white and it would give you a state where both speakerphone and 3.5mm headset are on at the same time. Otherwise you'll need a switch that will short red/blue and orange/white seperately when in the "on" position. i.e. a DPST sub-mini switch.

On the back of the phone there's a spot just next to the headset jack that looks like a perfect place to mount a switch. However this will be at the back which may not be suitable for many users.

Take a sub-mini switch to connect the red-marked soldering pairs to turn speaker on manually after connecting headset.
(This solution is copied from http://www.ip-phone-forum.de/showthread.php?t=94873 thanks to dfroe!)

Turning your GXP2000 into a conference phone.

I've found the speakerphone for the GXP2000 to be barely adequate for 1on1, so for a group sitting around the phone it's not good enough. I've started working on a fix using the 2.5mm headset socket.


1) 3.5mm stereo male to 2xRCA female adator
2) RCA male to 3.5mm mono female adaptor
3) 3.5mm Condensor Boundary Microphone
4) RCA male to twin RCA female adaptor ( splitting the signal )
5) 2xRCA male to 1x3.5mm stereo female adaptor
6) Pair of powered PC speakers with 3.5mm stereo male plug

The RED RCA from part 1 plugs into the male RCA on part 4. The female RCAs on part 4 plug into male RCAs on part 5. The 3.5mm from part 5 connects into the 3.5mm plug from part 6.

The White RCA from part 1 plugs into RCA from Part 2. The 3.5mm from Part 2 connects to part 3.

Plug the 3.5mm stereo from Part 1 into the headset jack of your phone. If you've connected it all correctly you should hear a tone from the speakers when you hit the "Speaker" button.

I have found the Mic pickup is very quiet and am hoping if I plug some sort of amp between the MIC and phone it will sort that problem out.

Created by: username_taken, Last modification: Mon 21 of Jul, 2008 (22:58 UTC) by linker3000
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