The M4 DataPhone
service can also handle voice, fax, e-mail, audio, video and internet connection.
The first modems to use Comsphere are leased-line models that can be programmed with any of the three diagnostic protocols used by AT&T Paradynes's Analysis, Dataphone
II, and Comsphere 6800 Series network management systems.
Here, Pru-Bache keeps T1s, M24-compatible muxes, Dataphone
2 modems connecting to the front end, and other equipment.
Previously, AT&T customers with high-volume communications traffic had to choose between a full T1 link or a 56-kb/s Dataphone
Digital Service (DDS) link.
There also are a series of 56-kb/s DDS (Dataphone
Digital Service) lines in the network and a few 9.6-kb/s analog lines.
Dial-up V.32 modems cost you less than an analog leased line or DDS (AT&T's Dataphone
Digital Service Network) 9.6kb/s data line.
AT&T Information Systems' family of Dataphone
II products includes a 9.6-kb/s modem that offers multiplexing capabilities and advanced diagnostics.
Hewlett-Packard has also enhanced the HP 4925A bit-error-rate test set to handle Dataphone
Digital Service circuits that employ V.35 interfaces.
II Level IV, the most advanced product in the Dataphone
line, has the ability to manage and control larger, more complex data networks than any similar system, according to AT&T.
One of AT&T's first moves in entering the international data transmission services arena was to link its Dataphone
Digital Service with similar service offered in Canada by the Trans-Canada Telephone System.
The bandwidth of the T1 is often less expensive, per bit, than multiple analog lines or DDS (Dataphone
Digital Service) circuits of the same aggregate capacity.
During 1974, AT&T initiated its Dataphone
Digital Service (DDS), establishing the first nationwide, end-to-end, private-line digital data service.