iPhone 4S
Hello, I have a problem, now tell in detail. When I bought my iphone 4S (18.11.11), it was ios 5.1.1 and the speaker, which is used in conversation (near the front camera) worked very loud, and I'm happy about it. after I updated to ios 6, he became quieter twice, but I was too happy with, it was optimal. but after upgrading to 6.1.3, he began to work very quietly, in the street do not hear anything at all. Dynamics of the net, he wore a service center - everything is fine. but the problem persists ... you can not tell how to set back ios 6.0 or other solutions.
thanks in advance
iPhone 4S, iOS 6.1.3