Hmmmm ?? I've only just clicked on the link above that Kitz provided (GEA service test), and that very much looks like a non-intrusive test to me ??
That was a GEA test run on my line - it definitely disconnected me when I asked PN to run one for me.
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ETA
From KBD
GEA (Generic Ethernet Access) Service Test (E2E Test in standalone menu) – Fibre products only
This fibre-based test is the equivalent of the copper line test, Status Check, Local Access Network and DLM Data checks seen for
WBC copper. It is also referred to as the SFBB (Super Fast Broad Band) test to BT Wholesale users.
The following criteria may be displayed within the test:
• The overall GEA test outcome returned as a result of the diagnosticsran
• A description of the fault should a fault be found
• An indication if the circuit was in sync when the test was ran
• Downstream and Upstream sync rates
• DSLAM profile
• Circuit performance parameters.
• Fibre based RRT style results
• If an appointment is required or not for any ‘Fail’ results
All GEA Service Tests run via New KBD are set to intrusive. This allows a copper pair test to be run for the copper section of Fibre to the Cabinet (FTTC) circuits.
If the ISP performs a Copper Line Test or CIDT via the TSAM, this has ability to interrupt both voice and/or DSL. Depending upon the test type, once the SP has connected to the test head, relay switches can isolate various parts of the network exchange side from the MDF. Usually this means anything after the handover frame.
The SP could if they wish just test exchange side ie from Test head to MSAN which gives them the dial tone... rather than the EU line out via the MDF.
There's a total of 4 states: 1 normal and 3 test. 2 of the test states are fully intrusive. The last one isn't intrusive but that doesn't have the ability to test various line conditions such as loop, atten & a couple of other things required by the RRT & KBD which must be run before Openreach will accept a fault.