25 and 27 would already be on a duct system so the new connection duct to the new cab could have a tie cable to both 25 and 27 in it.
Either way it extends the length of your end connection compared to putting FTTC next to cab 27.
I wouldn't expect cab 25 to have connections for cab 27 in it originally, either each will have their own E-side cable to the exchange or the connection into cab 25 will be taken off a common cable in an underground joint box. Based on looking in the odd hole, no inside info !
MaxDSL - goes as fast as it can and doesn't read the line checker first.
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