The Analog Line

The Analog Line

As we in the telecom industry look around this digital, wireless world we live in, it is easy to dismiss our analog past.  While we don’t dispute that companies such as Avaya, Nortel, and Cisco have offered us amazing advances in telephony, we are reminded that analog is not gone, nor should it be forgotten!

The Analog Line is Dead! Not Yet…
Published on August 16, 2010
by Gary Audin

(Ed. note:  The original version appeared in Nojitter Blog.)

Two questions I ask of a client who is moving to an IP-PBX are, “What non-phone lines do you have on your PBX? What analog lines do you need to support?” Most of these lines are more permanent than those to telephones and rarely need to be moved or reassigned, and are forgotten. People move around but the non-phone devices usually have a long and static location.

It is almost always true that they are and need to remain analog, and it becomes an issue with the IPT gateway that supports the non-phone devices. It is also annoying to many managers who anticipate retirement of all analog lines and devices. So before thinking you can eliminate them, read on about cases where these will continue operating for many years. Here are common examples:

  • Analog fax machines that operate the T.30 standard.
  • Dial-up modems, mostly for PCs and possibly point-of-sale devices and credit card readers.
  • Alarm system connections.
  • Telemetry systems.
  • TDD.
  • Elevator phones.
  • Secret lines for special conditions such as a whistleblower connection.
  • Analog phones in otherwise unoccupied buildings.
  • The janitor’s closet.
  • Phones in common areas that have little physical security.
  • The guard shack that is hundreds of feet from any building and can only be economically accessed on an old analog line.
  • The phone line outside a building that is used to call the guards for off-hours access.
  • Emergency phones as a lifeline to the PSTN.
  • Warehouse phones where it is expensive to install Ethernet lines.
  • Supervisory control and data acquisition connections that are designed for analog lines.
  • Intercom and announcement lines.

The analog line in the enterprise, government or educational institution is more common than the average telecom person realizes.  When I write an RFP for IP-PBX procurement, clients invariably keep finding more analog lines in use that must stay as such for the foreseeable future. Another advantage is that some analog devices can be powered by the legacy PBX. This must be supported by the gateway, or they will not work.

I recommend:

  • An extensive inventory of all devices connected to the PBX and carriers before issuing an RFP or entering into a contract for legacy PBX replacement.
  • Not assuming any of these analog devices will automatically disappear when an IP-PBX is installed.
  • Polling your security department to see what devices are now, or intended to be, connected to the PBX.
  • Engineering, manufacturing and health groups be polled to see what they assume will be connectable to the IP-PBX that may still operate on analog lines.

Another reason to continue using analog lines is to avoid installing LAN cabling. One company, Phybridge, has the ability to extend Ethernet devices over analog lines with their special LAN switch. This allows the organization to recycle an existing asset (analog lines) and reduce cabling cost.

There have been too many occasions when some of the analog devices will not be supported, or supported poorly, on a gateway. Consider using DSL modems in-house to connect to lower-speed Ethernet devices over analog cable.

IT staff rarely have any idea of the connections to non-phone devices. When they drive implementation of the IP-PBX, most of the time they come up short on analog device support. Organizations may have to order analog lines to the PSTN to support some non- phone devices because the gateway does support them. This may occur after the IP-PBX vendor has installed the gateways, and means these device connections are separate from the organization’s control and may create security problems.