Short Range Tactical Comms Using 'Old'Nextel i355 Phone?

Started by RadioRay, July 24, 2013, 12:40:06 am

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Does anyone here have experience using the Nextel iDen / "WalkieTalkie" feature on these phones?  They are 'old' phones and so seen as door stops by most people and I have found them on E-bay used for $15-25 on E-Bay and etc.  Here is why I am considering them

1.   They are frequency hopping transceivers, greatly lowering the probability of intercept by almost anyone other than a three letter agency.

2.   They PROBABLY use the telco CODEC for audio during the hops, because analog audio cell phones are MUCH older technology than this. If they DO use the CODEC audio then this would make it 'practically' impossible for an non-governmental-entity to intercept and listen to audio. ((though there is one guy I have seen work who might be able to do it, if he leaves Germany with his European team and comes here with all their computers and cellphone hacking equipment during a societal meltdown with this specific goal in mind.)) ... Not very likely.

3.   They match my need for SWAP (Size, Weight & Power) and price!  They are inexpensive.

Without using modified antennas, the range is various listed as 1-3 miles, which for home security is fine.  If I implemented this, I would likely run an external gain antenna from the house, using a modified phone/"base station" with good, hardline to extend the range. As we all know, antennas are the FIRST go-to, not power.

>de RadioRay ..._ ._
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry



They can be set to a phone-to-phone DIRECT mode. 

And they DO appear to use the CODEC even while phone to phone in frequency hop mode.  Here is a close range, FAST find intercept of what EXPENSIVE equipment, close enough could heard, if some looter were actually THAT technical.
youtube of captured signal.
"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry


I found an on-line copy of the users manual, and I'm a little confused.  They say:

QuoteYour phone has 10 channels and 15 codes.

Channels are divided into sets of frequencies that
allow you to make and receive Direct Talk calls.
Other parties may also be talking on the same

Codes help minimize interference from unwanted
messages and other disturbances when you are on
the same channel as others.

They go on to say you can set the phone to receive all codes, so that sounds like FRS.

But then they say:

QuotePrivate Direct Talk Calls

You can have a private conversation with another
person using Direct Talk. When on a private Direct
Talk call, no other parties can hear your
conversation. In order to make a private Direct Talk
call, you must use the valid Nextel 10-digit
Personal Telephone Number (PTN) of the person
you are calling. The person you are calling must be
in Direct Talk mode and set to the same channel to
receive your call.

If you receive an error message:
? You may not be using a valid PTN.
? The person that you are trying to reach may not
be in Direct Talk mode.
? The person that you are trying to reach is set to
a different channel or is out of range.

So it sounds like a dual mode system with an FRS type radio unless you use an actual device telephone number to get security.  But, I don't know - I've never seen or used one so I couldn't say.  It takes SIM cards, so I don't know if a PTN could be spoofed for the purpose of using the Private Direct Talk.

The manual is at



I remember people using these at a place I used to work.  They make the typical cell phone user talking on his phone in the middle of a wedding seem mild.


Apparently you need a valid SIM card to transmit coded, even P2P. 600mW output.



There is mixed information on that.  One fellow, who seems to be technical, said that you need a SIM card to set it up initially, but not to use it in walkie-talkie mode once it is set-up.  I'll continue to look into this for comms around the house and for fun.

"When we cannot do the good we would, we must be ready to do the good we can."  ~ Matthew Henry


In video 2 of the series Gil linked to, the guy demonstrated using the Private function with phony self-entered phone numbers but he didn't say how to do it.  That would negate the part of the instruction manual I mentioned above.  Apparently he did it from the keypad.

That video series looks pretty impressive.


This has me intrigued, I'll keep an eye on this thread.

I do wonder though, do they have built in keyers and the ability to use the phone pad as paddles or do you have to use an external keyer? 8)
"Those who would give up essential liberty to purchase temporary safety, deserve neither liberty nor safety" - Benjamin Franklin



A little follow-up on entering "phony" phone numbers to activate private mode... the comments section of Part 2 to the video Gil posted had a link to a thread in another forum.  There was a link to another video in that thread where the presenter demonstrated this works with more models than just the I355 - including the I570.  In another video a presenter shows editing the phone information screen to put in a phony number by editing "Line 1".  I found the I570 manual on line and it is more clearly written than the I355 manual.  It says:

QuoteYou can also edit the information in Line 1, Line 2, and Circuit Data, but your changes are only temporary. The next time your phone registers on the network, your actual phone numbers and circuit data number appear again in My Info.

Since we are talking about phones without service, any number you put in should stay there.

There was a lot of information in the thread on the other board and there seem to be a lot of utube videos on these phones.


medic photog

When we were mobilized to go to the World Trade Center after 9-11 our USAR team took all our gear and set up our commo system as usual.  The local system and cell net was overrun and down more that it was up so our radios did most of the work, that is until it went down and took a while to get up and running again.  We relied heavily on NEXTEL direct connect from the rubble pile to the base of operation (BOO).  next after the Nextells were some Motarola GMRs.  not as dependable but they worked close in, like one side of the pile to the other, then retransmit on the Nextell.  I can't go into detail about what kind of radios we used or what frequencies we were on, unit security and all that, but USAR teams carry everything they need to be self sufficient for 72 hours and that includes food, water, shelter.  There's a lot of stuff in those unmarked tractor trailers.