In 2014, I had a similar problem so I created Cosmos Browser, an Android based internet browser which allowed people to connect to the internet via SMS. It's pretty much dead now, but wouldn't take a lot of work to revive it if you really wanted to.
Without actually looking through the code, I have a few questions:
1. How slow is it loading webpages? I think SMS would be a little sluggish since each message can only contain 160 characters.
2. How do you guys manage out of order text messages? Is there some sort of metadata that governs the order of a multi-part SMS?
Thanks so much for posting this - really a blast from the past.
Our process was
1. Remove all JS and CSS from the HTML file
2. Compress the file into a gzip stream
3. Base64 encode the file
4. Send it as a stream of text messages with some metadata on sequence numbers, etc
SMS uses the GSM 03.38 encoding which is a 7 bit encoding. I think we were working on building a custom encoding scheme for it rather than using Base64's 6-bit encoding, but never got around to it.
I think reddit.com (back in 2014 when it wasn't so fancy as it is now) took about 20 text messages to load, so you can imagine it would take less than a minute.
Edit: I also want to add that I've looked into UCS-2 encoding (here: https://www.twilio.com/docs/glossary/what-is-ucs-2-character... ) but I'm not sure if the decrease in characters per message (only 70 instead of 160) is worth the greater amount of characters (theoretically 36,864 but probably includes many non-usable characters). It would also require a more complicated encoding algorithm, and I'm not sure how well supported this is by carriers internationally.
You should put up a github repo when you're done, regardless of how you feel about the way the code looks. It will absolutely help during a job search.