The F1 is the feeder cable coming from the Central Office (CO) to a junction point known as an OPI or JWI. From the OPI or JWI there is then a series of cables going out to the neighborhoods - the F2 cable. The F2 feeds the aerial terminals or pedestals, which then have drops going to the house.
Every facility feeding a customer is currently made up of an F1, F2 and drop cable.
In FTTN, the F1 cable is used to feed the voice from the CO to the OPI or JWI located DSLAM (i.e. the fibre fed node in the field). The DSL is then added at that point.
The only thing the F1 is used for in FTTN is to feed dialtone - the DSL is added at the F2 point. If Bell switches to an IMS architecture with derived voice (i.e. VoIP) generated by an adapter at the home, similar to a cable EMTA, they no longer need the F1 to feed dialtone to the OPI/JWI.--
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