This section does not cite any sources. Please help improve this section by adding citations to reliable sources.
This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. However, the FCC's seminal Carterfone Decision ofthe FCC concluded that electronic devices could be connected to the telephone system as long as they used an acoustic coupler.
Since most handsets were supplied by Western Electric and thus of a standard design, acoustic couplers were relatively easy to build. An even lower-cost option was the Pennywhistle modemdesigned to be built using parts from electronics scrap and surplus stores.
Like the A, it used different frequency bands for transmit and receive. It was similar in design, but used the lower frequency set for transmission.
According to Vadic, the change in frequency assignments made the intentionally incompatible with acoustic coupling, thereby locking out many potential modem manufacturers. Carterfone and direct connection[ edit ] This section does not cite any sources.
October Learn how and when to remove this template message The Hush-a-Phone decision applied only to mechanical connections, but the Carterfone decision ofled to the FCC[ who?
This opened the door to direct-connect modems that plugged directly into the phone line rather than via a handset. However, the cost of passing the tests was considerable, and acoustically coupled modems remained common into the early s. The rapidly falling prices of electronics in the late s led to an increasing number of direct-connect models around In spite of being directly connected, these modems were generally operated like their earlier acoustic versions — dialing and other phone-control operations were completed by hand, using an attached handset.
A small number of modems added the ability to automatically answer incoming calls, or automatically place an outgoing call to a single number, but even these limited features were relatively rare or limited to special models in a lineup.
When more flexible solutions were needed, third party " dialers " were used to automate calling, normally using a separate serial port to communicate with the dialer, which would then control the modem through a private electrical connection.
The introduction of microcomputer systems with internal expansion slots made the first software-controllable modems common. This led to a series of popular modems for the S bus and Apple II computers that could directly dial the phone, answer incoming calls, and hang up the phone, the basic requirements of a bulletin board system BBS.
The seminal CBBS was created on an S machine with a Hayes internal modem, and a number of similar systems followed. October Learn how and when to remove this template message The original model baud Hayes Smartmodem In later years, USRobotics Courier modems were common at many BBS's because they had better compatibility with more brands of modems The next major advance in modems was the Hayes Smartmodemintroduced in This allowed both data and commands to be sent through a single serial port.
The now-standard Hayes command set included instructions for picking up and hanging up the phone, dialing numbers, and answering calls, among others.Overview. ETSI NFV ISG undertakes work in 2-year phases. Documents published during the first phase () were considered as pre-normative studies, .
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