I have cobbled together using my TTI TCB-550, an old relay (which may have been used in the now-closed FRN gateway), and my existing interface that I rewired for the VV-898 a few years ago, with a very crude adaptor that converts the VV-898 connector to one that can plug into the TCB-550 into a Zello gateway, the Zello app runs on my shack computer reconfigured for gateway mode, it then listens either for activity on the CB channel the radio is tuned to, or from those in the channel logged into Zello on their phone, tablet or computer.
I didn't have a smooth sailing with it because the relay lost its common pin (it sheared off once wires were soldered onto it though I repaired it with a ball of solder) and working out which wire went to what on the VV-898 connection was a challenge, the audio out of my CMI8738 soundcard was unusable for this so the audio connections were all made to the onboard sound in the computer.
The CB transmits fine, and it receives fine (local testing from handhelds puts a buzz on the transmission but that's from operating them surrounded by electrical items), the CB in question was also used in the now-closed FRN CB Gateway, though I since removed the fan on it.
The CB is putting out the expected 4 watts, and an antenna is still required to go up to make it of any use, that's a work in progress given the antenna limitations I have here at this QTH.
Once the antenna connection is complete then I can transmit from my car's CB in the local area to any device running Zello in which the user of that device has access to the group the CB gateway operates from, and vice-versa, however I do not have a permanent computer to dedicate to such a task in the shack right now so it would only operate if I was out of the house.
And the best bit is, as Zello is used, any messages not picked up immediately can be replayed by the Zello users to catch up on, it would not work for radio side.
My plan with this is for the Zello side to only allow those I know to have access to it, the CB side I obviously have no control over as is the nature of CB, and neither the TCB-550 nor Thunderpole T-3000 (which I use in the car) have CTCSS, obviously the first person getting access is my XYL who can then contact me over the CB like she did when she was here.
73 de M0WNU/26CT730