Smart metering is really a ...

Smart metering is really a system, not a meter.  There are many elements:

1) the meter may be a total replacement meter, with additional capabilities (on-off, system sensing) or an electronic radio transmitting device at detects the signalling in the existing meter and translates it to a digital format. The reading is then transmitted via a network.  Usually the transmission will occur on a schedule, and may contain reading at multiple shorter intervals.

2) the network will generally carry the reading to a head-end server.  this server will control the reading process, validating that the meter is on the system, and that the reading has been received.  If the reading has not been received when anticipated, it may send a signal to the meter to request the missing read.  The headend server may also manage firmware updates to the meter itself and the security protocol for the meter system.

3) the headend will generally aggregate the meter reading for a given period and forward them to a meter data management application where the data can be analyzed and used for billing or other business processes.

Systems tend to be proprietary although, for example, many meter data management applications can process data from different proprietary headend systems.  Some of the cloud based systems, which is the U.S. generally use the cellular networks for transport of the readings, provide the full range of services through billing, and customer presentation of usage information.