DigiTally: Piloting Offline Payments for Phones

Khaled Baqer, Ross Anderson, Jeunese Adrienne Payne, Lorna Mutegi, Joseph Sevilla

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Mobile payments support a range of services in many less developed countries including everyday payments, migrant remittances, credit, tax collection, and welfare benefits. These services depend entirely on the mobile phone network as their carrier, so they stop where the network does. This leaves millions of the very poorest people stranded - people living in remote areas where there is little to no network service. It also leaves urban users at the mercy of network congestion.We developed a prototype system, DigiTally, which lets users make offline payments by copying short strings of digits from one mobile handset to another. Offline payments are already used for electricity (both in prepayment meters and pay-as-you-go solar); can we extend them into a general-purpose payment system, to increase service resilience in the face of network congestion or outage, and provide service to currently excluded areas?We report the results of a preliminary study with an early prototype of DigiTally, tested on participants from a university in Nairobi (Kenya). The code-sharing process presented a possible usability challenge. To explore this and other aspects of an early prototype, DigiTally was introduced to Kenyan participants in order to resolve any major issues before a later field trial.We discuss the lessons learned from our field visits and initial evaluation; we hope that this contribution is helpful for researchers and policy makers interested in mobile payments and financial inclusion. We also present our findings and observations. We found that, although offline payments involve copying codes in both directions between the payer's phone and the payee's, the extra workload was acceptable to most users.
Original languageEnglish
Title of host publicationProceedings of the Thirteenth USENIX Conference on Usable Privacy and Security
EditorsMary Ellen Zurko, Sonia Chiasson, Matthew Smith
Place of PublicationUSA
PublisherUSENIX Association
Number of pages13
ISBN (Print)9781931971393
Publication statusPublished - 12 Jul 2017
EventThirteenth Symposium on Usable Privacy and Security - Santa Clara, United States
Duration: 12 Jul 201714 Jul 2017
Conference number: 13

Publication series

NameSOUPS '17
PublisherUSENIX Association


ConferenceThirteenth Symposium on Usable Privacy and Security
Abbreviated titleSOUPS 2017
Country/TerritoryUnited States
CitySanta Clara
Internet address


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