NEC ux5000 Hardware Manual page 208

Chapter 3 - Installing Extensions and Trunks
1. Remove the bridging clips on the (A) block and telco block for the DID lines.
2. From the telco block, solder the Tip lead to the "3" connector on the choke.
3. From the telco block, take the Ring lead and solder it to the "1" connector on the choke.
4. From the (A) block, take the Tip 1 lead and solder it to the "4" connector on the choke.
5. Solder the Ring 1 lead from the (A) block to the "2" connector on the choke.
6. Reinstall the bridging clips as required.
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