Can I receive sound in both ears using headset with fixed phone? I have a Sennheiser headset (3.5mm) and a Gigaset phone (2.5mm). I am converting with a jack adaptor. The headphones work perfectly on a mobile but not on the fixed phone, I can only hear through 1 ear. I have tried 3 convertors, all with 2 or 3 black bands so should be stereo. Gigset have said that I should receive in stereo but it's just not happeneing. Any suggestions please?