The audio-fingerprint which commands a central function for the identification of automatically inputted calls has been enhanced. It consists now of a sequence of 20-bit vectors that allow for an efficient index based search. The individual signature vectors are sufficiently robust for one-way functions to be used for protection against any potential reconstruction of audio contents.
On October 10, 2011, the study project Wählziffern-Extraktion und -Verwertung aus RTP-Strömen unter Verwendung des passiven SIP/SDP Stacks callx (Digit Extraction and exploitation from RTP streams by using the passive SIP/SDP Stack callx) is going to be presented by Herrmann Stünz. A functionality has been developed to enable the callee to tag unwelcome SPAM calls by pushing a button. The digits are being extracted as DTMF-tones directly from the RTP stream and are allocated to a call. The results can be used in the VIAT project for the pre-selection of calls.
On September 29, 2011, R. Marjianto has presented the master thesis Entwicklung und Integration von signalisierungsbasierten Verfahren zum Schutz vor Telefon-SPAM (Development and integration of signalling based processes for protection against telephone SPAM) which evolved in the context of the VIAT project.
Mr Marjianto has examined various processes of SIP signalling analysis, as well as developed software for data retrieval and analysis, and integrated the same into the SIP server SER (Kamailio). The results can be used within the VIAT project for the pre-selection of conspicuous callers.
At the occasion of the project meeting taking place on Tuesday, June 26, in the University of Applied Sciences, Mr Julian Strobl presented his master thesis “Entwicklung einer effizienten Suchmethode zur Identifikation von Sprachdaten und Integration in ein System zur Abwehr von Telefon-SPAM” (Development of an efficient search method for the identification of language data and integration into a telephone-SPAM-controlling system).
Afterwards, the status of the project, the current work, and the further aims in the third year of the project were discussed.
Already during the previous year an operating prototype (Rel.1) was implemented, as reported by Mr Lentzen a few days ago at the IEEE ICC Conference 2012. By developing an efficient index based search method for comparing audio-language data by Mr Strobl, the performance can be considerably enhanced by Rel. 2. Also Mr Grutzek with his further enhanced audio-fingerprint, and Mr Mainka with the VoIP overall integration delivered some important input for the VIAT prototype.
Index-based algorithms accelerate the search for replayed spam calls. The results of the study were presented by Julian Strobl at the conference DAGA 2011 in Dusseldorf.