As the family told also, at least two phone calls were made from 35000ft altitude. That means the FBI lied about these calls. Why did they lie? Because the cellular phones could not work at such altitude.
The phone calls are not evidence for the official story, they prove that the official story is white lie.
Again, you cannot know what you claim to know, unless you have direct evidence of perjury on the part of the FBI. And if you really did have evidence, any of you truthers could use it to prosecute the FBI - it wouldn't be too difficult. But since the evidence exists only in your minds, you can't do anything but accuse them of lying - but really it's probably you who is lying.
That also doesn't account for the airphone records, unless you accuse the airlines and airphone companies of also lying. But of course you have no evidence of that either.....
Most peculiar in your thinking is that you purport to know more about the phone calls than the people who actually received them. Not one of the people who spoke with victims of UA93 had trouble identifying the callers as people they knew. Spouses, sons, etc...
Yet you, and others like you, claim to know that those weren't the real people they were speaking to. The fact is you don't know, and you can't know, what you claim to know. Reality isn't just something you make up in your head, like your claims of magic voice morphed phone calls.
Unless you could produce direct evidence that phone calls were fake (which you cannot except by misrepresentation) then we must accept they were real, and that your claims are wrong.
If you can produce a phone record, from the phone company, which proves what you claim, you should stop making the claim, and stop accusing the FBI of lying. You have no business continuing to do so unless you produce real evidence.