Originally Posted by
cairnshouse
This plane flies west over the populated land of a relatively sophisticated country. Yet no-one with any recollection of UA 93 makes a call from a concealed phone.
Keep in mind that on 9/11 much of the US still had AMPS cellular service, and there were many dual mode AMPS phones about. AMPS is now completely deactivated in the US. Some countries never had AMPS, and began service with GSM. AMPS had longer range and better coverage than GSM.
If people were able to actually place cell phone calls from UA 93, it may have been over AMPS (although one mention way back in this thread suggested they used a special aircraft phone service).