Inbound calls to one line cause other line to ring

Question

Scenario:

• Residential
• Two VOIP telephone lines served by two Cisco SPA-122 boxes
• Each SPA-122 connects to separate Line 1 and Line 2 junctions in the house basement
• A single, 2-wire cable connects a wireless telephone to Line 1
• A single, 4-wire cable connects a 2-line desk telephone to Line 1 and Line 2

The problem:

Inbound calls on Line 2 will ring Line 1 once and display the CID on the wireless telephone during the CID cycle.

In other words, BOTH Line 1 and Line 2 ring and display CID on inbound calls to Line 2.

The Line 1 wireless telephone only rings once, even as the line continues to ring Line 2 on the desktop phone.

Tried:

Completely disconnecting the Line 1 SPA-122 from the circuit. Problem happens.

Completely disconnecting the desk telephone, down to disconnecting the wires from the wall jack. Problem happens.

Completely disconnecting the 4 wire cable that supplies the desk phone from the basement junction box. Problem does not happen.

Connected a new length of 4 wire cable to the junction box and tested with it still wound on the spool, leading no where. PROBLEM HAPPENS.

It's as if inbound calls on Line 2 are jumping / inducting cross-copper to Line 1 and ringing the wireless phone! Is this possible? How can it be fixed?

Answer 1

Is the 4 wire cable the type with 2 twisted pairs? If so, you may have the jacks wired incorrectly, such that the each telephone circuit is using 1 wire from twisted pair A, and one wire from twisted pair B. This would lead to increased and perhaps excessive electrical coupling from pair A to pair B.

If the 4-wire cable does not have 2 twisted pairs, then using a 2-twisted pair cable will reduce crosstalk between your two lines (provided you make sure that line 1 uses twisted pair A, and line 2 uses twisted pair B).

Answer 2

Evidently, the two VoIP base units and any satellite (extension) phone units have the same Bluetooth name. It is probably not the offending base unit that is ringing, but its satellite phones. The satellite (extension) phone stations are linked to its respective base unit, but since both base units have the same ID name only one base unit will ring, but all extension phones will ring because they will receive a signal from either of the base units. The fix: Rename one of the base units and link its satellite units to the new name.