There are many factors that affect your quality of service that you can't see. Other radio transmissions can interferer with your reception along with electromagnetic waves. Just about anything that uses electricity gives off some electromagnetic interference. Just the electrical wires running through your walls will give off some interference.
Something is changing, its just something you cannot see.
And different phones have different sensitives to interference too.
That's just how it is. Some spots you get really good service, others are bound to go out after awhile. My room is one of those spots ...
is it at&t? because some phones from that service do that alot