Failure to disconnect a call properly: who's fault is it?

LazyTyper

JohnDinton wrote: »

See this BT Openreach document about changes to First Party Clearing on BT analogue lines.
http://www.openreach.co.uk/orpg/home/updates/briefings/wholesalelinerentalbriefings/wholesalelinerentalbriefingsarticles/wlr00314.do

Another good read are the BT SIN notes http://www.sinet.bt.com/sinet/SINs/pdf/351v4p6.pdf

7.1. Terminal Initiated Clearing
7.1.1. By The Calling Terminal
When a call is ended by the calling terminal, the BT network interface will detect an off-line
condition (see section 3.1 Off-Line d.c. Condition) and provide the network initiated clearing
(see section 7.2 Network Initiated Clearing) to the called terminal. Line breaks of less than
200 ms will not be recognised as a clear. Line breaks greater than 3 s will be recognised as a
clear (see section 10.1 Follow-on Call).

7.1.2. By The Called Terminal
When a call is ended by the called terminal, the BT network interface will detect an off-line
condition (see section 3.1 Off-line d.c. Condition) and initiate a time-out process lasting
between two seconds and three minutes. After the time-out period has expired, network
initiated clearing (see section 7.2 Network Initiated Clearing) is provided to the calling
terminal.

Although this is only relevant for lines provided by BT or are on BT's WLR3 platform. The OP is with TalkTalk so it's up to them what these time-outs are and how call clearing is handled.

Another good place to check is the NICC who develop interoperability standards for UK telecom operators - http://www.niccstandards.org.uk/

Buzby

This is irrelevant to the complaint. If the first party DOESN'T initiate a clear (as in the case described) the charging is correct. If a technical error caused the lack of a cleardown (the users instrument) then the network is not responsible unless the phone was supplied or rented by them.

Called Terminal clearing is fine if this is supported by the system called, but as this appeared as a call in progress, there would be no reason to terminate the call.

JohnDinton

It is relevant because if TalkTalk had implemented First Party Clear properly there would need to be two faults for the call not to be cleared after the expiry of the timeout after the called party had cleared. Also SaffronFlower says the handset was replaced correctly.

LazyTyper wrote: »

Another good read are the BT SIN notes http://www.sinet.bt.com/sinet/SINs/pdf/351v4p6.pdf

Although this is only relevant for lines provided by BT or are on BT's WLR3 platform. The OP is with TalkTalk so it's up to them what these time-outs are and how call clearing is handled.

Where does it say that SINs do not apply to LLU providers? Although the SIN says it is BT copyright, it also says some of the standards are ETSI standards. Since there is national type approval for customer equipment it would be unworkable if LLU providers could set their own standards. In the case of the recent changes to First Party Clear to combat fraud, it would be an invitation to the fraudsters to target the customers of LLU providers if those LLU providers were not required to implement the same changes.

LazyTyper

JohnDinton wrote: »

Where does it say that SINs do not apply to LLU providers? Although the SIN says it is BT copyright, it also says some of the standards are ETSI standards. Since there is national type approval for customer equipment it would be unworkable if LLU providers could set their own standards. In the case of the recent changes to First Party Clear to combat fraud, it would be an invitation to the fraudsters to target the customers of LLU providers if those LLU providers were not required to implement the same changes.

BT SINs are technical descriptions of BT services. LLU providers are not BT, so why would the SINs apply?

JohnDinton

Because the LLU providers need to interwork with BT equipment and cables. What will happen if one of them wants to use equipment that operates at a line voltage of 500V instead of 50V, or 5V with a line current of 250mA, or a tone signalling system that uses codes incompatible with MF4?

The only example of departure from a SIN I can think of is Caller Display. The SIN for Caller Display is different from the standard used in some other countries, including the US. For Caller Display to work on a BT line it is necessary to use a device which supports the SIN, and they used to be a lot more expensive. I have a feeling that on Mercury exchanges it was possible to use Caller Display devices which only worked on the US standard.