How can users respond to Twilio SMS messages routed through third-parties?

0
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I'm part of a public health project that using text messaging to increase the access to health care that disadvantaged groups have in South Africa.

The project intends to create two-way text messaging between one "sender" phone and many "recipient" phone to disseminate health information.

The issue

The first message we send arrives as intended. However, the number relayed to the recipient as the source of the text is not our number. That number, moreover, is non-functional.

According to customer support, when SMS messages are delivered to certain countries, such as South Africa, Twilio changes the sender ID (SID) before passing the message to local carriers to work around local filtering mechanisms. (Before they did this, many messages didn't get through.)

Twilio customer support says that changing the SID makes two-way SMS communication impossible with Twilio in these countries?

Can anybody think of an alternative or work-around? For example, is their a way to store the original sender ID and revert back to it when the recipient replies?

2
smstwiliotelephony
Hi! My company (connecting college students to mentors) may be building a similar system, and I'd love to ask you some questions about it. Which countries were affected by this issue? Were there any gotchas (aside from this one) to watch out for? (My email is [email protected]). - Eli Rose

2 Answers

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Twilio Customer Support here.

I can appreciate that this is a frustrating situation, the best solution that I can think of to workout the substitution of your sender id is to include a 'Reply to' number in the body of the message.

Whilst this not ideal and would consume some of the message body, your end customer would at least know which number to reply to.

Regards, Tom

1
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(Disclaimer, I work for Nexmo, a communications API.)

This is less a Twilio issue, and more a carrier issue. Nexmo provides a carrier specific FAQ listing what happens to the senders for each country. While that may or may not reflect what happens with other SMS APIs / aggregators, it's a good indicator of what's possible in a specific country.

As Tom says, you can include the number in the message body. However, another solution that may work as an alternative is USSD.

Where supported (and that's not everywhere), you can send a USSD with prompt through Nexmo. It doesn't require a sender, and the response is returned through a callback. In some cases it's better than SMS, as you know exactly what message the user is responding to, and the nature of USSD means you'll get your response quickly (as most of the time the device will pop it over whatever is currently on the screen).