In the UK, we used to use a station auxiliary power supply "SAPS". It was a small power supply unit that was fitted at the phone end to boost the current.
Other countries will probably have different versions.
The UK book has..
Station Auxiliary Power Supply
The Station Auxiliary Power Supply (SAPS) is a plug top power
supply that uses a standard 240 V ac, 50 Hz mains socket. It provides
a 24 V dc supply that enables devices to operate on longer extension
loops. The SAPS should not power more than one device.
SAPS for system telephones
For connection of a system telephone, the cabling is polarityinsensitive.
1. Connect the dc output pair to pins 2 and 5 of the telephone line
socket using a block terminal 80A or equivalent. This method is
recommended since the dc pair uses tinned stranded wire.
2. Plug the SAPS into a working mains socket and test the
telephone.
Firebird Scrambler
Nortel & Avaya Meridian 1 / Succession & BCM / Norstar Programmer
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