Helsinki University of Technology Delay-Tolerant Networking @ TKK Comnet Department of Communications and Networking


DT-Talkie is a DTN-based voice messaging application that enables mobile users to communicate over infrastructure-less and challenged environments in the walkie-talkie fashion. DT-Talkie supports both one-to-one and group communication. DT-Talkie is primarily implemented for Maemo based Nokia Internet Tablet. We port DT-Talkie application to heterogeneous endpoints like Mac, Linux PC and Openmoko based smartphone as well. DT-Talkie is now available also for Symbian.

The idea is that if User A wants to talk with User B, he presses a button (fullscreen hard button of Nokia Internet Tablet) after selecting User B's EID (Endpoint Identifier) and start talking. After finishing the talk, he presses the button again. Then DT-Talkie forwards his voice message over the DTN infrastructure destined to User B. On the other end, User B can hear the voice message as soon as it is received. User B communicates with User A using the aforementioned approach.

System Architecture



Audio C/P


Bundle S/R




DT-Talkie Screenshot

Individual Contacts: list of EIDs used in one-to-one communication

Group Contacts: list of EIDs used in group communication

Pending List: list of voice messages which have not been played back yet

Active User: shows sender's EID and profile picture as soon as a voice message is received.

There is a text entry box in between the individual and group contact list to input EID that is not available in the list. There is also a add-up and a add-down button along with the text entry box to add EID in the appropriate contact list.


The DT-Talkie installation instructions are given for Nokia N810. The instructions are also applicable for Nokia N800 if OS2008 is flashed to the device. dtnd must have to run in the system before launching DT-Talkie application. So we also provide installation guidelines for dtnd if it does not run in the system.

dtnd installation

DT-Talkie installation

You can also get DT-Talkie version 2.0 and DT-Talkie version 1.0 debian package.


Md. Tarikul Islam: Voice Communication in Mobile Delay-Tolerant Networks. Masters thesis, Helsinki University of Technology, 2009. [PDF]

Md. Tarikul Islam, Anssi Turkulainen, Teemu Kärkkäinen, Mikko Pitkänen, Jörg Ott: Practical Voice Communications in Challenged Networks. Accepted for publication at the 1st Extreme Workshop on Communications. Padjelanta National Park, Lapland, August 2009. [PDF]

Md. Tarikul Islam: DT-Talkie: Interactive Voice Messaging for Heterogeneous Groups in Delay-Tolerant Networks. In Demo at IEEE CCNC 2009. [PDF] [Poster]

Md. Tarikul Islam: DT-Talkie: Push-to-talk in Challenged Networks. In Demo at ACM MobiCom 2008. [PDF] [Poster]


This work was funded by Nokia Research Center and CHIANTI project of EU FP7 programme.

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