Polycom vtx shows incoming call and when picked up i only hear my voice what could be the issue?

SOURCE: I CANNOT HEAR THE INCOMING CALL VOICE

problem with speaker contact service center

SOURCE: NOKIA 1600 I CAN HEAR THE VOICE WHILE THE OTHER

Your MICROPHONE is not working.Please get it replaced

SOURCE: Static from SoundStation Premier

Check the phone cable you are using for your POTS line. Attach a phone directly to the phone jack and see if it is clear or static without the device.

SOURCE: I can't hear incoming call

During a call, you can adjust the volume as you normally would, using the + and - buttons on the side.

SOURCE: Polycom soundstation 2 not showing

The link below may help you on resolving the issue. This is a PDF file for user guide:
http://www.orficn.net/Verizon%20Website/Phone %20Manuals/audio_conferencing_polycom_soundstation2_user_manual.pdf
Just click it. Please let me know if this help you or not so that I will proceed to the other solution.