file 703 question

[akai-kun]

The bomber said he didn't want police and also, a normal thing is that if you were a bomber, you wouldn't like the police know about you also, or?
But if people can telephone someone else or the police or send SMS, that isn't given, so he can't have an accomplice who looks after these mobile phones because he can't do it himself or everyone will know that he is the bomer, so...

[akai-kun]

thanks.

no problem, you're welcome

[sstimson]

There might be more to that answer. The guy with the bomb could have said the bomber told him to collect all the cell phones, but he did not.
Police like to know what is going on inside a hostage case. That way they can best plan when to make their move. By not collecting the phones, the bomb guy could not know if anyone was spying on him or not. He can not possibly watch everyone at once. It is interesting as to why he did not tell them to put their phones near him. But He did not do even that. And I think Conan decided that there could only be one bomber when no one collected the phones.