08-04-2020 08:01 AM
08-04-2020 11:39 AM
All New Zealand mobile networks operate A2P (application to person, ie bulk machine-generated) SMS on a whitelist only basis because of the high prevalence of spam and scam SMS. That means we only accept A2P messages from about 12 direct trusted bulk messaging partners, and each business sender those partners sell to must be pre-registered and be allocated a shortcode they can send from. Shortcodes are caller identification, they are like car registration plates and must be unique to each business sender who writes the message.
Previously Twilio was sending via our direct partner, SAP, from shortcode 5872. This shortcode was blocked by SAP and VFNZ on 16th April 2018 (ie 2 years ago) because it was used for an ANZ bank phishing scam. This code was being used on a shared basis, we don’t allow sharing of codes (any more than you can share car registration numbers) for the precise reason that we don’t want to block innocent senders when we have to block scam SMS.
About a month ago we had a Business customer contact us about Godaddy 2FA SMS not working, Godaddy also uses Twilio. In that case we worked with SAP, and SAP advised Twilio is no longer using SAP, we talked to our other largest A2P partners and were unable to find anyone selling A2P SMS to Twilio. In that case we also did testing with the Business customer and established that the messages are not reaching the Vodafone NZ network (we are able to see attempts, even if they are being blocked by Vodafone). All A2P partners work hard to block scam and spam messages and it appears that either a downstream partner is blocking, or Twilio is simply not sending – the Twilio Godaddy 2FA SMS were not being blocked by Vodafone. The Business customer even tried porting to Spark and the Twilio Godaddy SMS did not work on Spark either.
Any New Zealand business using an overseas provider for A2P SMS should insist that their provider (eg Twilio) is using dedicated shortcodes that identify each business sender that is writing the messages. And beware of whether a “cheap” service actually works, there are a number of global operators who simply attempt to find security holes, and bill for a “best efforts” service, and claim unsuccessful messages are being blocked by spam filters.
Unlike email (which is a blacklist model, where everything is open initially and problem traffic is blocked), Vodafone New Zealand does not actually operate a spam content filter for SMS (although our trusted partners operate their own spam filters). A2P SMS is a whitelist model, and only trusted senders can send A2P SMS (“blocking” entails removing the shortcode from our whitelist).
If you can advise any more details like whether the messages are working currently on Spark or 2degrees (and on which shortcode), we can try to do further investigation with our A2P SMS partners. But to reiterate, you need to raise in the first instance with your overseas A2P SMS provider as to why they are charging you for a service that does not work.
09-04-2020 10:36 AM
Many thanks for such a detailed response, my big question is why we cannot use NZ numbers, this would provide 2-way communicatio options with our customers.
With the POS system we use Twilio is the only option for SMS and their dedicated shortcode offering is proibitively expensove for us as a SME.
In Australia users of the same POS system can purchase AU numbers through Twilio - with a requirement to provide identification for security and SPAM prevention and this seems to work extremely well.
When we first noticed that SMS messages were not getting through I tried on numerous occassions via a number of channels, including a communication with yourself, to trace where the issue was but was unable to find any assitance.
Through a personal contact at 2degrees and Twilio support we were able to trace a number of specific numbers and they were all VF numbers and they were being sent to VF successfully, therefore indicating the blocking was being done by VF. No 2degrees numbers were being blocked.
Again the biggest outstanding question I have is why we can't secure NZ numbers for SMS callerid.
Any suggestions as to how to progress this issue would be appreciated.
09-07-2020 03:15 PM
I'm jumping in here a little late, but it is 3 months on from this original comments in this thread, and I have found that Twilio is not able to deliver to Vodafone customers.
@sebastianbd thank you for the detailed background information. You have asked for more details about whether people on other carriers are recieving SMS messages from Twilio.
I can confirm that when I send messages from Twilio, they are received successfully by users on Spark and Two Degrees. It is only Vodafone users that do not receive the txt messages via Twilio. I have tested it this week with 2 Spark users, 1 Two Degrees user and 2 Vodafone users. The Spark and Two Degrees users received the SMS messages instantly. The Vodafone users never received the SMS messages - even though we have tried multiple times.
So it is specifically something to do with Vodafone or your upstream provider. The logs in Twilio state that the carrier network (Vodafone) has replied saying the message has been delivered.
We have tried contacting Vodafone support and spoke to the mobile technical team, but they didn't provide any help at all. They just said everything looks fine and refused to open a ticket to investigate further. Very frustrating! They didn't seem to have any knowledge about Twilio at all, so knew a lot less than the information you have provided.
The NZ shortcode that the messages are being sent from is 338.
I'm happy to provide more detailed information, including logs, if that helps with troubleshooting. Feel free to call me if that helps. My number is the 021 number shown on this page: https://www.duoplus.nz/contact/
10-07-2020 09:10 AM
We finally found a solution, according to Twilio Vodafone increased the aggesiveness of thier spam filtering and so have started blocking loads of messages.
We applied for, and were granted Carrier Whitelisting and have not had any issues with blocked messages since.
I'll send you the instructions to apply.
13-07-2020 10:17 AM
Thanks Richard. I spotted the instructions earlier on in this thread on how to apply for whitelisting. I've now been granted whitelisting status with Twilio and Vodafone customers are now receiving the messages, so it works! Thanks!
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