Ok, I've just come back from two weeks in Israel, and it works.
Before you leave, you must have customer service activate your phone
for international service (ie: roaming), but presuming you have an "i"
phone listed on the Nextel site, it works fine.
My handset showed the service provider as NIDS, which appears to be
the roaming portion of the
IDEN provider there.
People calling your domestic U.S. number will ring through to your
handset in Israel. Outbound calls are Israel-local (as if you were
dialling from a landline there), and U.S. domestic calls can be made
by adding the + (hold down 0 for 1 second) and dialling as usual. I
did not try international dialling to third countries.
Dispatch and packet data services were restricted. One-way text
messages were delivered. Voicemail notification was delivered.
If there are any other questions, please post a followup.
John