signal strength *send* by my phone When I get a call, I often can hear the other side just fine, but they don't hear me. This happens so often that I wonder if the problem could be my phone's sending signal strength. (There are tons of apps showing the received signal strength, but this is not my point.)


Is there a way to measure or configure this?
Is this a possible explanation at all?


Edit: should have added that the call is often dropped some seconds after I become inaudible. I hear the other side crisp and clear complaining about me not audible and then it drops.

Further I discovered the Settings -> About Phone -> Status -> SUBS Status (my translations from German) where I see that the connection is difficult in these situations (UMTS at -95dbm to -103dbm). 

The model I am envisaging is that the receive (from cell) and send channels (to cell) are slightly asymmetric, due to walls, buildings and other obstacles, such that the phone software underestimates the necessary sending power by a few percent.
Sending strength:  Modern digital cellphones are set to utilize the minimum power to maintain a connection.  So the fact that the connection isn't dropping completely tells you that you have sufficient RF signal strength to make and receive calls.

Talk Volume:  As for them telling you that your voice is not loud enough I would suspect the microphone itself.  Like maybe pocket lint got into it or it got poked with something.

If it is an older phone it is possible that some part has failed or is in the process of fading.

In order to properly diagnose this, I would want to know 1) Did this start suddenly, or has it been a gradual change?  2) Can you send texts?  (They require sending power to connect), and 3) How has the phone been treated?  Has it been dropped or anything like that?

With the little information you provided I would look closely at the phone itself. 

And you can rest assured you are getting enough sending power.  Digital is not like old phones where it can connect but you have to yell because of bad amplifiers in the central office.  With digital, you can either connect or not, period.  If the circuitry canperform their internal handshakes that maintain the connection then you are fine.  If the error rate goes up, your phone will automatically raise its signal strength until the celll network is happy enough to maintain the connection.  

That is enough diagnosis to determine your signal strength is sufficient.