Definition

Machine-to-machine communication

Also known as: M2M, machine to machine, telemetry

Machine-to-machine (M2M) communication is automated data exchange between devices without human involvement — meters reporting consumption, controllers reporting status, systems accepting remote commands.

How it works

A field device initiates a session on a schedule or when an event occurs, transmits its data, and disconnects. Legacy M2M frequently used dial-up modems over analog lines; modern equivalents use cellular data, but the field equipment is often too embedded or too long-lived to replace, so the analog interface has to be preserved.

Why it matters

M2M lines are the easiest to forget in a migration inventory precisely because nobody uses them interactively. A meter that stops reporting produces no complaint — it produces estimated billing, or a fault that goes unnoticed until someone visits the site.

Common use cases

Utility meter reading and automated consumption reporting
SCADA telemetry and remote control of field equipment
Environmental and equipment status monitoring

Low visibility is the risk. An M2M line that fails generates no phone call — only a gap in data that may not be noticed for a billing cycle.

Common misconceptions

“M2M lines are low priority because no one is on the phone.”

They are low visibility, not low importance. Unreported meter data and undetected equipment faults both carry real cost, and neither announces itself.

Frequently asked questions

How do I find M2M lines during an inventory?

They rarely appear as 'phone lines' in records. Look for lines terminating at equipment rooms, plant rooms, meter cabinets, and roof installations, and check for modems attached to control systems.

Can legacy analog M2M equipment be kept?

Usually yes. An appliance presenting an FXS port lets the existing modem dial as before while the transport moves to cellular, which avoids replacing embedded field equipment.