Is there a way to link ERDM repeaters to a larger network using IPSC or similar?

Q. Is there a way to link ERDM repeaters to a larger network using IPSC or similar? There are a lot of conflicting information around the internet some saying yes they can be linked using IPSC, others saying it is not possible. Another says they can only be connected to a dispatch software like TrboLink or via a Smart PTT dispatch console.

A. ERDM (Extended Range Direct Mode) [a.k.a. Single Frequency Repeater] is a MOTOTRBO repeater feature that enables repeater-like operation using a single (simplex) frequency. When configured to operate in this mode, the repeater receives on timeslot 1 and repeats any incoming transmission on timeslot 2 (90ms later). Similarly, radios - configured for this - receive on timeslot 2 and transmit on timeslot 1.

ERDM does not support IP Site Connect and is strictly a single site solution designed to extend RF coverage on a single frequency. It can however connect via IP network to a wireline dispatch application like SmartPTT and others (I've not heard of TrboLink). In principle, using this, you could patch talkgroups on multiple ERDM repeaters to create an IPSC system of sorts.
The trouble with this, is that the system is dependant on the dispatch application being online and connected. In this case, the 'system' will not generate beacons and so it wouldn't be possible to roaming like in a real IPSC system.

Because ERDM timing and framing are designed for a single-site simplex channel, a repeater cannot participate in the wide-area floor control and arbitration procedures required for IP Site Connect. More importantly, you'll notice that, enabling ERDM on a digital channel automatically greys out or disables any IP Site Connect channel selections.

Remember that if you are going to use ERDM, the repeater either needs two separate antennas or a high-speed antenna switch. A duplexer will not work nor will an antenna relay - it has to be a high speed switch that can handle the RF power.

In some countries, there also be spectrum licencing implications.

In EMEA at least, the repeater(s) needs a Extended Range Direct Mode licence (HKVN4490A). I don't know what the other regions' part numbers are off hand.