The firm's first product, introduced in 2007, is a USB device that has both the software necessary to place Internet-based telephone calls via a customer-supplied high-speed Internet connection and the electronics (technically known as a SLIC, or Subscriber Line Interface Circuit) which allow conventional landline telephones to be plugged directly into the device.
Phone numbers belonging to MTNL start with the prefix 2 in fixed line telephones and WLL.
Dursanchar government under take to private C-DOT, ITI, MTNL, BSNL and Airtel provide fixed landline postpaid PCO connections.
Such contribution links are often made by terrestrial connections (landline, fibre, etc.) but the use of a satellite "hop" provides advantages in some situations.
Digital telephones lack the mechanical acoustics and circuitry that used physical wiring to produce sidetone in older landline phones, so digital phones include electronic circuitry, software and firmware to reproduce sidetone.
In the satirical 1967 film The President's Analyst, "TPC, The Phone Company," is depicted as plotting to enslave humanity by replacing landlines with implanted mobile phones.