Telekom Deutschland GmbH now also offers a change of the ISDN PABX connections to SIP telephony in the modernization of traditional TDM technology to IP-based communications. This conversion (often under the pseudonym title "ALL-IP") involves the exchange of ISDN multiplexers (S2M) / ISDN NTBA (S0) with certified IP routers e.g. Telekom. These routers provide the connectivity to the Internet used for in- and outcoming connections by the OpenScape 4000 SIP trunking to the Central Office (CO).

An alternative is the so-called “DeutschlandLAN SIP-Trunk Pure” by Telekom. This includes no access (xDSL/FTTH) by Telekom and can be used with any Internet connection (bandwidth dependent) where Telekom Sales should be contacted for more details. For guaranteed speech quality (Quality of Service) by Telecom a DeutschlandLAN SIP trunk with access service provided by Telekom is required (e.g. xDSL, FTTH).

For OpenScape 4000 perspective this means the connection must be moved from a classical ISDN Board to a SIP-compatible Board in terms of both board and LCR Routing configuration.

On OpenScape 4000 side these changes are supported with existing virtual HG boards (SoftGate) as well as the SIP-compatible STMIX/STMIY and STMI boards.