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I'm using the clickatell.com platform to send SMS from my app to my user.

It's really just to get a one-time-pin. Nothing more.

It works just fine for everyone except for some (random?) users. Some of them are iOS7 others are iOS8, so I'll assume it's not version related.

Situation :

  • On clickatell : The SMS is clean, has the right number, shows the right provider and that provider is successful in delivering SMS to my other users. Everything is tagged as delivered to handset and all is wonderful on that side. They send their messages from +## xxxxxxxxxx regular numbers, not "8603" or something short like that.

  • In the code : He uses the same code as everyone else and the code returns no error (otherwise an alert would show). So we also "assume" it runs smoothly there. All of my users run the same version of the app and use the exact same code no matter what (no preferences/special users/etc.)

  • The device : They have non-jailbroken iPhones of version going from 7.1.2 to today's latest. The same device asked for the pin several times without getting it. We tried a week later without changing anything and the SMS went through. He is obviously not on Plane mode and has data active as well as network. We've tried on plane mode or in a faraday cage (actually it was a bag of crisps), we get an error message just like it should.

  • The testing : I've tested on iPhone 4S -> 6 on iOS 7.1 -> latest. Works fine. Every. Single. Time. I've also contacted clickatell this morning but they were of no help. I've asked if they've had this kind of situation before though in hope they can point me in the right direction and... they couldn't.

So, finally, we're getting to it : My question.

What could possibly prevent a user from receiving an SMS from clickatell.

I have no idea where to look. I could show you code but it's pretty much a copy-paste from their documentation except it has my access keys...

Are there settings? apps? SOMETHING??

EDIT 1 : Clickatell answered my email and was (to keep it short) of no help.

EDIT 2 : I know this is a horrible question to investigate because you have nothing to work on ; neither do I. I'm really looking for hints/directions (or even a solution) but I don't expect you to type a magical line of code that will fix everything. Really if you have an idea just shoot it in the comments or an answer, I'm not here to downvote if it's not complete enough, I'm just here to get those SMS to go through...

Gil Sand
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  • Did you try to ask that from clickatell support team? – Azat Apr 09 '15 at 15:57
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    Yeah, as I said in the post, I did :) – Gil Sand Apr 09 '15 at 16:07
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    Disappointed to see a down vote here. Though there isn't any programming discussed here, but still it's a valid question which shows the person has investigated and put in all his efforts to debug a problem. May be the question is better suited to some other forum. – Rahul Sharma Apr 09 '15 at 16:30
  • I dont understand why i got downvoted here. If whoever did that could at least bother leasing a comment... – Gil Sand Apr 10 '15 at 06:41
  • Unlikely but possible is the user blocked the number. Though unlikely I have seen it happen. We send transactional notifications via SMS and ask the user to add the phone number as a contact and yet we have had users block the number and then call asking why they don't get the message. – jimrice Apr 15 '15 at 07:43
  • The user didn't intentionally block the number, that is for SURE. But do you think the operator might have done it? (even though it delivers with the same number to other users of that same operator) Or do you think a user could've a blocked phone number UNintentionally? – Gil Sand Apr 15 '15 at 07:46
  • If you could get delivery status message from ISMG rather than from clickatell.com, it would be more helpful. – nickcheng Apr 16 '15 at 08:43
  • Could you elaborate? What is ISMG? – Gil Sand Apr 16 '15 at 09:18
  • They could have unintentionally blocked it either because they weren't paying attention or ... I have had users unintentionally block the number despite instructions to add the number as contact and even providing a vCard. Users can be unpredictable. What kind of logs does clickatell offer? I use twilio for an SMS gateway and they keep all logs with delivery status and times. I have found it very useful to prove the message was delivered. When a user says I did not get it I ask them to check their usage online for that specific time and sure enough it was delivered like it says. – jimrice Apr 17 '15 at 06:59
  • The logs aren't really that great, I can see the sms was delivered to the gateway (sms provider), and that that gateway sent the SMS successfully to the handset. And... that's it. Also i'm 99% sure that my user hasn't blocked any number. one of the test devices is pretty much out-of-the-store and didn't recieve any of the text messages either. – Gil Sand Apr 17 '15 at 09:50

1 Answers1

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When you send a message via clickatell, the API returns an API message ID (a unique reference number for every message submitted). Could you please give me a couple of API message IDs for the failed messages, and I can escalate this for further investigation (with the network operators, if necessary).

Disclaimer: I work for Clickatell

Flexo
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Arno
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  • These messages never got received by the reciepient. 3a6c167ba6444695de32a54a4b8196d8 // 1dc38a45bbd72a3ad2f0aebafcdb30e9 // 6a93bc8af9a428e37101ad471bcd1e14 // 52ecc80a0cc7844e8ec6a9d79f701b51 // Man I really hope you can get me through this :) – Gil Sand Apr 17 '15 at 14:16
  • I've escalated to our delivery engineers, and although delivery to Belgium isn't reporting any problems, the message IDs pointed to a specific area of the routing network, and we've made a small adjustment to delivery in that network. Could I ask you to try again and let me know if the delivery is working better? – Arno Apr 17 '15 at 14:50
  • So you think it could be location related ? Or am I not understanding? – Gil Sand Apr 17 '15 at 14:52
  • Also, other question : can I test now or is there some time needed to adjust this network delivery? – Gil Sand Apr 17 '15 at 14:52
  • On it. i'll tell you more in a minute – Gil Sand Apr 17 '15 at 14:52
  • Okay this is my luck, the guy just left to madagascar (like an hour ago) for two weeks. Ain't life grand... Is there any point to test that now or because he's probably 100km away now, it's not the same "grid" ? – Gil Sand Apr 17 '15 at 14:55
  • You can still test, unless he is using a different SIM card and different mobile number. the network I was referring to is the different network suppliers and how they route messages between each other, so if he's still using the same mobile number, the same routing should apply. – Arno Apr 17 '15 at 14:57
  • Okay ! We asked him a minute ago, hopefully he'll read the text and I'll keep you updated. Otherwise i'll message you here again in two weeks... Good job though, I'm happy that you could help – Gil Sand Apr 17 '15 at 14:58
  • I'm heading out, but I'll check the thread in a couple of hours. I hope this helps, though! – Arno Apr 17 '15 at 15:04
  • Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/75542/discussion-between-arno-and-zil). – Arno Apr 17 '15 at 18:29
  • I'll stay on chat all day hoping you get online soon ! Its 10AM here and we'd like to release this week so I really hope we can sort this thing out. I'll be in the chat :) – Gil Sand Apr 20 '15 at 07:52
  • Hi, any update here? We are sending over 350 messages in one go and some of them are not received. The same numbers sometimes are receiving and sometimes are not. Cliclatell says - received by user. – vt100 Jul 02 '15 at 16:11
  • Hi, vt100. Contacting the support helpdesk with information like the message API IDs should help them troubleshoot the problem. Zil's problem got sorted out successfully. – Arno Jul 04 '15 at 14:59