SIP Provider Deutsche Telekom, SIP Trunk & SIP Trunk Pure (DE)

The information published here applies both to the SIP Trunk standard, which is dependant from the Internet connection of Deutsche Telekom, and to the SIP Trunk Pure.

The SIP Trunk of Deutsche Telekom was first tested and released with a SwyxWare 2015 R3.5.

Deutsche Telekom is offering a SIP trunk with user authentication. You have received information about UserID, UserName and UserPassword, whereas the naming may differ, or you might have only received UserName and -password. In this case, UserID and UserName are identical. 

DNS configuration

Basically the DNS server of the respective Internet access provider should always be entered on the SwyxWare server (or router).

DNS in the VoIP environment for Telekom connections

For Telekom connections with PPPoE dial-up (xDSL), these are automatically assigned when dialing in. For CompanyConnect (CoCo)/GermanyLAN Connect IP (DCIP) as well as for Business Premium Access (BPA) these are stored on the customer letter. There must be no confusion between CoCo/DCIP and BPA DNS servers!

The DNS server for the respective product must always be used. In the worst case, incorrect configuration can lead to SIP trunks not being registered, to temporary problems (e.g. dropped calls) or to Quality of Service (QoS) not working. The customer should therefore know whether he has a CoCo, DCIP or BPA.

DNS in the VoIP environment with third-party access

If the customer uses a third-party access (e.g. Vodafone as carrier line) the DNS servers of the provider should also be entered. If these do not support eDNS and ECS, the address 9.9.9.11 of the third-party provider Quad9 can be used. Internet access via Telekom LTE is also considered third-party access (voice products via LTE are currently not released).

Under no circumstances should Telekom DNS servers be used for third-party access.

Platforms

SwyxWare
The SIP trunk of Deutsche Telekom can be used without restrictions from SwyxWare 2015 R3.5. When using an earlier version of SwyxWare incompatibilities cannot be excluded and use is at your own risk. However, the standard SIP trunk is linked to Deutsche Telekom's Internet connection, whereas the SIP trunk pure can be operated on any Internet connection.

SwyxOn
Due to the dependence on the connection with standard SIP trunk or due to further technical restrictions, the connection to the SIP trunk pure must also be made locally at the customer via a suitable gateway. Configuration instructions for a LANCOM gateway are available for download at the end of the KB article.

Configuration

During creation of the SIP Trunkgroup, profile 'Telekom Trunk TCP (DE)' must be selected.
If encryption is required, profile 'Telekom Trunk TLS (DE)' must be selected. It is mandatory to import the DTAG Root Certificate into the into the Windows-Certificate store of the SwyxWare server. Additional information (in German) can be found as download link at the end of this article.

Required information:

• Access number (previously T-Online Number) or Telephony-Username, i.e. 11223344
• Personal password for the Telekom SIP Trunk
• assigned number range, i.e. +49 401122330 - +49 4011223339

This information is provided by Deutsche Telekom when the connection is created or can be accessed through the Telekom customer center.

As UserId for the created SIP Trunk, the first number of the available number range has to be configured, i.e. +49401122330. User name is the Access number (previously T-Online Number) or Telephony-Username respectively.

In the codec dialog, G.711u and G.729 can be deselected, T.38 as supported codec must be deselected.

FAX Transmission

The Telekom SIP Trunk does not support the T.38 protocol, which is strongly recommended for FAX transmission in an IP environment. The alternative method for FAX transmission via G.711 is supported from SwyxWare2015R3 on. In oder to prevent the intended T.38 stream switch, it is necessary to remove the T.38 codec from the list of supported codecs.

Note: Quality and reliability of a FAX transmission via G.711 strongly depends on the end-to-end network connection. Since the control and redundancy information from the T.38 protocol are missing, especially the transmission of larger documents may fail.

Tested Features

• Incoming/outgoing national calls
• Incoming/outgoing international calls
• Correct Calling Line Identificaion (CLI) on national and international calls
• CLIP No Screening
• Holding and retrieving calls
• Toggeling between two calls
• Call transfer
• Call forwarding
• Conferencing
• Mutually supported codecs:
  • G.722
  • G.711a
• Incoming/outgoing DTMF signaling in accordance with via RFC2833
• FAX transmission via G.711

Test dates:
02/09/2016 with SwyxWare2015R30.5
14/03/2018 with SwyxWare 11.10.2.0
04/12/2019 with SwyxWare 12.00.0.0

The third-party contact information included in this article is provided to help you find the technical support you need. This contact information is subject to change without notice. Swyx in no way guarantees the accuracy of this third-party contact information nor is responsible for it's content.

References