So I googled for feedback, and there's some in bitcointalk thread: https://bitcointalk.org/index.php?topic=1602801.0

Also reddit discussion: https://www.reddit.com/r/Bitcoin/comments/51fif1/dtmf_anonym...

This is cool, but the customer has to jump two technical hurdles: being able to pay with Bitcoin for the first time and using WebRTC for the first time. Perhaps the most likely customers are already fluent with Bitcoin and WebRTC. I have the feeling however that there could be a hundred times more potential users if the hurdles were smaller (or better explained).

Also, although I personally like the super-clean minimal web page, I imagine it'll look amateurish to the typical user. (Maybe this doesn't matter to the target audience.)

WebRTC is not a hurdle, every recent browser supports it.

Some things are subtly broken in different (current) browsers, and Safari 9 (the most recent wide-release version) doesn't support it at all. Check out the feature compatibility table: http://iswebrtcreadyyet.com

Stop 100 people on the street and ask them how they'd make a phone call through their browser (not even mentioning jargon like WebRTC). How many will know what to do?

I'll grant you that perhaps all that's needed is a better explanation and examples on the OP's web site.

(creator of DTMF.io here)

I don't see WebRTC as being too much of a hurdle. If the user is running recent-ish Chrome or Firefox, they don't need to know about WebRTC any more than you need to know about HTTP in order to load the website. It just happens to be the technology we use to make the voice calls work: you still type a number into a box and click a button and then talk.

If they're running Safari, they're unfortunately completely out of luck for now - but SMS will still work!

It would be interesting to turn this into a one-off CLI command [using 21](https://github.com/21dotco/two1-python)

(disclaimer: I work for 21 Inc.)

Thanks for the link, I'm going to look into this!

For some reason, I expect everything on HN to be free...

What I found interesting about this is the anonymity factor. Currently you can't get a GMail, Twitter, etc accounts without verifying it with a phone number via SMS or voice. This service supposedly solve this issue, but indeed if they rotate between a few mobile phone numbers they will be quickly banned.

Anonymity, yes, as long as you acquire bitcoin with cash, and don’t leave any identifying traces behind – the difficulty of which varies with each individual scenario.

We have a pool of numbers that changes size depending on demand, but we make sure to return them at the end of each billing period and buy new numbers. Between the providers we get numbers from, there is a very large quantity of numbers available.

that's the big concern i have with all this 2fa pseudo-security-bullshit. first, you don't get my fucking number. second, give me another 2nd factor choice. third, the gsm network is, as we all know from defcon and ccc, completely broken. why the fuck is anybody trusting the phone system, still? these are the instances that make me loose trust in the oh-so-educated tech world.

at least a service like this is needed. to fight the assholes of facebook and the likes.

How long until an intelligence service creates a system like this and turns it loose, only to be watching and listening the whole time.

How do you know an intelligence service didn't create this system, and turn it loose only to be watching and listening the whole time?

This is the vital missing piece, not the complete solution. For the rest, use the standard tools of online anonymity (Tor, Tails and so on).