I work for a US company that’s got an R&D center in India and we use Duo for 2 factor auth.
Recently I was switching phones quite frequently and hence I used the “On call 2nd factor auth” feature until I got my new device rebonded.
I noticed that every time I have to use on call otp, the Indian numbers cannot take the press of number X(used for confirmation/authentication).
Hence the call times out and I have to redo the authentication.
Then for the second/third time Duo falls back to a US phone number and that can take the input and finish the authentication.
Points to remember:
I don’t think my cellular operator is at fault here because the US call does take the DTMF code.
Luckily i had free incoming ISD, otherwise i might have ended up paying fees for every authentication call.
Every phone auth costs YOU an Indian Call plus an ISD call for a successful authentication.
Most other indian IVR systems work fine, and hence,
Your vendor has probably screwed up their India IVR, DTMF handling.
I just felt that I should let you folks know so that you may be able to address this potential money waster.