DMR MARC and Contact Calls (Private Calls)

DMR-MARC Canada operates a Canada-wide ham radio network based upon the DMR standard. This network uses Motorola MOTOTRBO DMR repeaters and is available for all licensed Canadian ham radio operators to use.

The Powers that control this network have decreed that Contact Calls(Private Calls) are NOT Allowed A request to have this overturned met with the following response.

sorry, we cannot grant your private calls request because we do not want to exclude people from hearing all traffic on the system.  Person to person calls are better made on a mobile phone. 

Regards, Mike, AA9VI

My response to this was

  1. 99 % of all amateur calls on simplex, fm repeater, digital repeater ARE PERSON to PERSON with the exception of nets. This comment should  be totally ignored as out of context.
  2. Private Calls may have been private at one time but that is no longer the case. so lets rename this feature to Contact Calls as it is initiated by selecting a call from a contacts list. These contact calls can be monitored by any radio equipped with promiscuous mode or a monitor mode.(ie Simoco DMR)

Cons: The only con on record is we do not want to exclude people from hearing all traffic on the system. This is no longer a valid reason. Possibly the network masters are using antique motorola equipment that does not have the capability of monitoring these calls and this is what scares them.

Pros:

  1. A contact call can locate the intended recipient across the network on whatever repeater or talk group he last checked in on.
  2. The contact call is Not PRIVATE and CAN be HEARD by any other station with Monitor MODE or promiscuous mode.
  3. A contact call from one side of the Canada to the other would use a lot less resources than a voice call on CAN TG302. In both cases they would move to an alternate tg ie TAC310. A contact call would only use the source and destination repeaters, just like an on demand call. A call on CAN would key up every repeater in Canada.

The powers that control this network have either a god complex or have lost touch with reality. The network is evolving around them and they are not keeping up. Sounds like a bunch of young boys playing sandlot baseball. Along comes a girl wanting to play, but denied because its boys only. They are not looking at the big picture regarding the best use of available resources.

Some user Comments  taken from the XPR Facebook pages.

Thomas Kvitle Jenssen I believe private calls are carried across the Internet, presumably to the last repeater the recipient was active on. Our local repeater outside Oslo Norway was used for quite a while the other day by someone talking aross the network to a fellow amateur with a New Zealand callsign. I was listening to their conversation using the promiscuos mode of the hacked Tytera firmware and I can positively confirm that unless you encrypt your traffic private calls can be heard by anyone with a hacked radio. (Encryption is not allowed in LA btw)
Seeing and hearing any activity, even private calls, on the timeslot is a very handy feature I hope the major brands will provide some day as well.

John Fraizer Private/Direct Calls are a great way to locate your buddy. If it’s going to go past a short exchange, go to a talk group. But, the network will automatically route a private/direct call to the appropriate repeater and not tie up a TS on others.

Corey Dean John Fraizer is 100% correct. It doesn’t matter what talkgroup you are on. This data, not a voice call, how ever it will send via the time slot you are using.

John Fraizer Private/Direct Calls are a great way to locate your buddy. If it’s going to go past a short exchange, go to a talk group. But, the network will automatically route a private/direct call to the appropriate repeater and not tie up a TS on others.

Colin ZapalacMonitor mode is a feature of Simoco DMR radios (no hacking required). If you use an sdr you can listen to a private call (it uses the standard CAI). All a private call consists of is a peer-to-peer call where other radios are polite and don’t decode the call.
Ken BoyleThe transmissions are not encrypted, you just cannot hear them because that is the way the radio was designed and programmed. It’s the same as a tg that is not programmed into your radio. It simply ignores it. Hacked firmware just makes it possible for you to change the parameters of the radio.

The BrandMeister network allows Group Calls and Private Calls.

Group Calls

A Group Call is a call to a talk group number, in which other stations configured to listen to this talk group will receive and broadcast this call. These other stations can respond in the same group call using the same talk group number. A list of commonly used talk groups is available below.

When using a Hytera station, you can manually dial in a group ID by selecting Contact in the menu, select Manual Dial and press # to switch between Group or Private ID.

Private Calls

A Private Call is a call to a specific DMR ID. This allows a single station to connect over the BrandMeister network to another station. The communication is “private” in that other DMR stations with a different DMR ID programmed won’t broadcast the QSO, but the communication is available for anyone listening in to the DMR stream or with a DMR station with an identical DMR ID programmed.