Interesting.
I'm with iakobos on this one.
I can't see how a BlackBerry (a digital cellphone) could turn up on 133.8, less still how the voice would be decoded by an AM airband (analogue) receiver.
The Blackberry (just a digital phone with extra bits) would be using GSM/GPRS which is a lightly-encrypted time-division multiplexed digital signal at 900MHz or higher. Ther is no way that you heard it in the clear in 133.8 MHz AM.
If it were a U.S. device, it might just have been a CDMA phone (code-division multiple access) -- same frequency bands, even less likely to be decoded as it's a spread-spectrum signal. But it wouldn't work outside the U.S.
You CAN decode FM signals on AM radio receivers by an effect known as "slope detection" -- but not digital signals.