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Testing Task Force T003:
TTCN-3 Maintenance and Testing 2020

Who we are:


Team management:
Team Members:

What we do

The Testing Task Force (TTF) T003 manages the evolution of the TTCN-3 in 2020 and develops in parallel the corresponding TTCN-3 tool conformance test suites. This includes the maintenance and further development of the ES 201 873 series of standards and the eight extension packages ES 202 781, ES 202 782, ES 202 784, ES 202 785, ES 202 786, ES 202 789, ES 203 022, and ES 203 790. The development of the TTCN-3 tool conformance test suites includes the maintenance and further development of the ETSI technical specifications TS 102 950-1, TS 102 950-2, TS 102 950-3, TS 103 253, TS 103 254, TS 103 255, TS 103 663-1, TS 103 663-2, and TS 103 663-3.

For more details, see our Terms of Reference

Why we do it

The TTCN-3 testing language has intensively been developed by ETSI during the last almost 20 years. By today, TTCN-3 has become a significantly important testing technology in different domains (see more details at It is used by standardization bodies as well as by EU research projects and open source initiatives. TTCN-3 reached very high deployment at various ETSI member companies. The language is also endorsed by ITU-T as the Z.16x and Z.17x Recommendation series.

In standardization TTCN-3 is an enabler technology for several conformance, end-to-end and interoperability test standards. 3GPP uses it for several UE conformance test suites from Rel. 8 onward, for LTE, VoLTE and lately for NB-IoT. ETSI TBs INT, ERM. In the C-ITS area several TTCN-3 test suites have been developed and they are playing important roles in ITS PlugtestsTM events, with automated C-ITS interoperability testing being in progress. In 2016 oneM2M has started using TTCN-3 for IoT/M2M conformance test development that has been continued in ETSI smartM2M from 2017. Other bodies and alliances using TTCN-3 are TCCA, EUROCONTROL, MOST, AUTOSAR and oneM2M (see more details at

In research at least 12 big projects from different domains are known to use TTCN-3, among them the EU projects MIDAS, IoT.EST, ARMOUR, PHANTOM, 5GTANGO and SMESEC (see details in at In the smart grid area CEAList has developed a model driven testing solution, using TTCN-3 to implement the user domain of the solution. The open source Eclipse project IoT-Testware is using TTCN-3 to develop conformance, performance and security test suites for IoT protocols with major contribution from Fraunhofer FOKUS and relayr ( The Osmocom project is an open source initiative implementing mobile communication standards, including GSM, DECT, TETRA, 3G and others ( and intensively using TTCN-3 for functional and regression testing. TTCN-3 plays an important role in the industry as well. TTCN-3 is used by several ETSI member and non-member companies as an essential test enabler language (e.g. Ericsson, Easy Global Market, Software Radio Systems).

Especially industrial users want low time to market of their new products. For this reason, they have introduced agile ways of working with continuous integration (CI) and continuous delivery (CD) machineries. Agile and CI/CD are heavily relying on automated testing (AT), including TTCN-3 based AT solutions. Resolving new requirements and user requests with short response time is important for user satisfaction and for keeping time-to-market low.

Significant number of TTCN-3 test toolsets are available on the market. At least five commercial tools, five free or open source tools and one internal test tool of an industrial ETSI member are known to exist ( This also indicates the high interest and use of the language. TTCN-3, as THE standard test language, serving several domains and application areas, is specified in very detail. For example, the TTCN-3 core language alone is estimated to contain about 5,000 requirements. It is of upmost importance for users of standard test suites as well as for industrial users that the TTCN-3 tools conform to the TTCN-3 language standards. This can be secured by TTCN-3 tool conformance test suites, in a similar way as implementations of other ETSI standards (e.g. protocol specifications) are checked by means of ETSI-developed conformance test suites. In the past, the TTCN-3 tool conformance test suite development process itself has led to several language standard clarifications.

TC MTS is committed to keep the language powerful still easy-to-use, up-to-date, well maintained and following the changing user needs. The series of TTCN-3 standards consists of 24 ETSI standards, altogether comprising almost 1800 pages and 3321 test cases in TTCN-3 code (145895 lines in 3702 modules) today. This commitment requires very high expertise and experts knowing the standards in detail.

How we do it

The TTCN-3 language evolution part of the work comprises the following tasks:
•    Review and resolve change requests reporting technical defects or requesting clarifications and new language features for all existing TTCN-3 language standards.
•    Develop proposals for language extensions requested by ETSI TBs, 3GPP, oneM2M, ETSI members and the TTCN-3 community and consent the solution with the contributor(s).
•    Implement agreed solutions.
•    Manage the change request (CR) process.
•    Manage the interim versions of the standard according to 3GPP needs (when requested), and the versions for approval.
•    Present the TTCN-3 standards’ status and the work of the TTF (previously STF) at the conference(s) associated with ETSI TB MTS and at ETSI TC MTS meetings.
•    Providing input for the updates of the TTCN-3 leaflet and the TTCN-3 web pages.

The TTCN-3 tool conformance tests part of the work comprises the following tasks:
•    Analysis of the latest published versions of the relevant TTCN-3 standards and identifying new and changed requirements.
•    Identifying affected existing test cases and define new test cases for the new requirements.
•    Implement changes and additions in the textual part of the deliverables (PICS, TSS&TP, textual part of the ATS).
•    Implement changes and additions in the code of the ATS.
•    Verification of the test cases with test tools.



The maintenance and further development of TTCN-3 is based on change requests provided by 3GPP, OMA, ETSI members and the TTCN-3 community. STF 550 resolves the CRs in agreement with the contributor(s) and produces new versions for those standards that are affected by resolutions. Potentially, STF 550 produces new versions of the ES 201 873 series of standards and the eight extension packages ES 202 781, ES 202 782, ES 202 784, ES 202 785, ES 202 786, ES 202 789, ES 203 022, and ES 203 790. In addition, the TTF will produce educational material and a TTCN-3 library for OO features.

Time plan

For all deliverables produced by TTF T003 the following time schedule is planned:

          Task / Milestone / Deliverable                                                                                                             Target date                                     
 Final Drafts of TTCN-3 maintenance deliverables  31-Jan-2021
 TB approval of TTCN-3 maintenance deliverables
Final Drafts of all remaining deliverables 31-Mar-2021
TB approval of all remaining deliverables
31-May 2021

How to contact us

For further details, or if you wish to be involved in the work of the TTF, please contact the TTF Management: Jens Grabowski or Andras Kovacs

This information is based upon STF working assumptions.

The views expressed do not necessarily represent the position of ETSI in this context.