Blåmba! ☎️ Behind the scenes of a 2000s-style ringtone provider (38c3)

A Deep Dive into WAP, SMS, monophonic ringtones and 1-bit graphics. A key part of early 2000s advertisements were hyperactive frogs and annoying crocodiles trying to lure people into subscribing to overpriced ringtones and silly graphics for their mobile phones. Apart from shady business practices -- how exactly do you send pictures and ringtones to vintage GSM mobile phones (most of which don't even support TCP/IP)? In our quest to learn more, we stumbled across WAP-Push, User Data Headers, Concatenated SMS, SMPP, User Agent Profiles and many more forgotten technologies. To put all this knowledge to good use, we built Blåmba -- a Chaos ringtone provider, clearly inspired by the (now long defunct) historic ones. Then at Chaos Communication Camp 2023 with the C3GSM network, we had the first public instalment of Blåmba. The Chaos community uploaded lovely artwork and new ringtones, sent patches for the software, and had a fun time reviving their old Nokia phones. This talk will tell the story behind Blåmba, explain how ringtones (and more) made their way onto your phone, what a WAP gateway did, and what other cool tricks mobile phones could do (if you had the money to pay for GPRS traffic 20 years ago). Licensed to the public under http://creativecommons.org/licenses/by/4.0 about this event: https://events.ccc.de/congress/2024/hub/event/blmba-behind-the-scenes-of-a-2000s-style-ringtone-provider/