SIP STX Lines Usage

BT Trading Recommendations for SIP STX Lines

The LSE Internet based TLS SIP trunk MUST be terminated on an SBC at the members internet connection point to provide a security boundary. This can be a dedicated SBC to the LSE service or it could be an SBC already in place to terminate PSTN based SIP trunks today.

The LSE lines are a Private Switched Telephone Network they are not Private Wires and so they need to be treated like the PSTN for this reason the SBC MUST be configured to send the SIP trunk on to the members PBX so that LSE numbers can be made available to any user in the organisation. The PBX can assign LSE numbers to phones for traders who do not have turrets or it can assign LSE numbers to BT turrets for traders that are on a trading system. There is no need to secure the SIP trunk between the PBX and SBC inside member network.

The LSE dial plan is only 5 digit and so will almost certainly overlap with existing member PBX dial plan and BT recommends the use of a dedicated partition and calling search space in the PBX to avoid clashes and also to restrict access to only those users that should have it.

To Connect the LSE numbers to a BTTrade SIP base trading system a number of BTTrade 3rd party SIP endpoint devices need to be created on the member PBX how many will depend on the number of LSE extensions needed. There may be a PBX license charge for this. Once created the LSE extension need to be allocated to these devices then the BTTrade TPO will register for them as for any other DDI lines on the PBX.

To Connect the LSE numbers to a BT ITS trading system a Voice gateway that can support QSIG is needed as ITS has no native SIP interface. As with the SBC a new dedicated voice gateway can be used but it is probably easier to send the LSE numbers over existing QSIG connections from the member PBX. It may be necessary to increase the number of QSIG connections depending on the number of LSE extensions needed. The member will be responsible for providing extra gateway resource but the DPNSS DLIC in the ITS that was terminating the existing service can be reconfigured with a software download to run QSIG if extra capacity is required.