I am using an iPhone 4 (Version 7.1.2 (11D257) ) I was given second hand about 18 months ago.
The issue I am asking about has not always been a problem. I used to hear the ringing without difficulty, but I have recently realised that the ringer volume has dwindled to almost nothing.
After discovering I had missed a number of calls, I checked the ringer in settings and when I experimentally play the different rings you can choose from they sound perfectly loud and unmissable, but when I dial my iPhone from our landline the ring is hardly audible at all.
I have pressed the + button on the side of the phone and in settings the volume shows as maximum.
I Googled the problem and found suggestions for how to remedy what sounds like a similar problem but the iPhone model they were referring to was different (newer, I expect) and the menu options in Settings seemed too different for the remedy to be applicable, but the fact that other people seem to have had the same sort of problem makes me feel that if I knew how it could probably be put right.