Beautiful Phone with weaknesses

During a telephone conversation I teach actually the main focus (ears shopping? :-) On the audio quality.
Annoys me eg in mobile phones, the devices are becoming more complex, but the original objective of the call, continue to meet only pretty mediocre, since the transmission quality is often abysmal.
These criticisms certainly not only to the mobile phone manufacturer is (distorting, crackling speakers, noise etc), but also the network operator.
Well, in this really beautiful, perfectly harmonized with the Fritz box Fritzfon C4 unfortunately also makes the audio quality to be desired. The speakerphone is actually very good and more than sufficiently loud, and also the interlocutor sees a well (no feedback etc). But the whole thing is garnished by a crackling crackling in the loudspeaker that bothers especially in quiet passages.
And the "normal" call without handsfree disturbs a significant noise in the earpiece, and often the maximum handset volume is just sufficient. Despite the latest hardware revision and firmware.
There was the sound quality of my old Siemens Gigaset 3000, in which unfortunately the Tastaur has given up the ghost, much better. As I had read in other reviews of the not so great audio quality of the C4, me a Gigaset E310A had incidentally ordered for comparison, the enthusiastic during my 80-year-old mother with its excellent audio and hands-free quality.
The Gigaset sounded better in fact! Because the hand flattering appearance and the great usability of the phone (especially by the perfect interaction with the Fritz box), I then but kept as technikverspielter ITler but the C4.

Another criticism: Unfortunately, you can also save any DTMF sequences with a phone number. I often use for example a Cisco Webex Conference Call number that I would like, together with a pause and an 8-digit meeting ID followed by another pause and a 4-digit access spinning save. This went so far with all my cell phones and even with my old Gigaset. By FritzFon'll never forget. Doing so would make sure easily implemented with a firmware update. I have, as other years ago, complained Support at AVM. Unfortunately, nothing is happening.

Oh, one more thing: The C4 has a 3.5 mm jack connector for a headset, and it works with the headset of my Samsung Ativ S perfectly.