Same SMS messages always fail to be received


    Hello. I work for a company that builds white label chatbots for financial institutions. One of the channels we offer the service on is SMS, leveraging twilio as our provider to enable delivery of SMS messages.


    I use my T-Mobile phone for receipt of inbound messages to test and demonstrate our technology. Recently, I'm experiencing behavior where the same exact messages in specific multi-part conversations will fail to reach my phone. Looking at twilio's SMS logs for these undelivered messages, they show a status of delivered to the carrier network (in this case that's T-Mobile).


    I asked another individual with T-Mobile to test as well and he experienced the same behavior (same missing messages). But my colleagues with other carriers are able to receive all the messages on their phones without issue. One additional note is that if I modify the text in the missing messages to remove certain key words or phrases, those new messages WILL be delivered to my phone successfully on a subsequent attempt. If I restore the text to the 'undeliverable' version, it will fail to reach my phone again. So at this point it appears something internally on T-Mobile's end is preventing delivery of very specific messages in a 100% reproducible way. Spam blocker has already been disabled for my account, and customer support has been adamant that there's nothing else which which would prevent messages from being delivered.


    I've spoken to multiple T-Mobile technical experts about this issue and opened at least a couple support tickets. I've received automated texts telling me the issue is resolved but no personal follow-up from any technical contacts at T-Mobile, and unsurprisingly the issue is not resolved.


    At this point I'm reaching out on behalf of myself personally (As a customer/recipient, I wonder why I can't whitelist all messages from a specific number regardless of what internal anti-spam countermeasures that number might be triggering)... and on behalf of my company (As a legitimate service delivering messages on behalf of established, FDIC-insured financial institutions, we'd like to better understand the reason specific messages might not be delivered to mobile end users).


    I've offered additional details and availability for joint troubleshooting to T-Mobile support. I can provide the originating phone number, my (inbound) T-mobile number, message SIDs, timestamps, and precise text for the missing messages. I'd hope all that information could enable you to to find some logs on the missing messages and determine a root cause. This issue is impacting me negatively on multiple fronts. I'd appreciate any assistance.

      All replies

      • tmo_mike_c

        We totally wanna help you as best as we can. What's the short code your messages are coming from? Has this messaging service ever worked before? Are you able to get texts from phone numbers? I suggest removing unique characters like symbols from the message and testing it again if you can. Sometimes unique characters may keep messages from being received.

          • magenta8601732

            Thanks for the reply tmo_mike_c.


            1. We don't have a short-code registered for the particular account sending these messages. The phone number sending the messages to my device is 3212046243.


            2. The messaging service has worked for as long as I can remember. Messages sent via Twilio using this phone number are received 100% of the time by my colleagues and were being received 100% of the time by me up until May 6. As of May 6, I still receive the majority of messages sent to me. But very specific messages are predictably and repeatably not received, despite being shown as 'delivered to carrier' on Twilio's end.


            3. As best I can tell, I receive all other texts just fine. But realistically, in general personal use I'd have no way to really know if a single message isn't received.


            4. There are no unique characters or symbols in the blocked message (aside from maybe an exclamation point), but there are definitely words or phrases I could see being blocked as part of a SPAM filter if there was suspicion of an illegitimate message source.


            This is the message that IS NOT received by my T-Mobile device:

            Great news! You're eligible for the Premium Visa Platinum Card and for big annual savings. You can view complete credit card terms & conditions here: (link to T&C page)

            Twilio Message SID for an occurrence of this message: SMf006c9836b2c61f543f362b0845357cd


            If I update the copy as follows, this message IS delivered to my T-Mobile device successfully:

            It looks like you're eligible for a new card with big annual savings. You can view complete terms & conditions here: (same link to T&C page)

            Twilio Message SID for an occurrence of this message: SMb5fbc239b4c9c5a98c5cbea20af1bdda


            Potential objectionable words/phrases I removed to ensure successful delivery:

            Great news!

            Premium Visa Platinum Card

            credit card


            It would be great to understand why the top message cannot be delivered successfully and whether or not, as an end-user on the receiving end of these messages, I can white label the phone number to ensure all messages are received successfully. I've included a representative Message SID for both cases above. Hopefully that can help identify why they're handled differently. And to reiterate, prior to May 6, the top message was being delivered successfully from the same originating number to my T-Mobile phone... so not sure what changed.


            Thanks again.

          • tmo_mike_c

            Hi again.


            Have you tried the steps in my previous post? Please let us know. Thanks.

            • magenta8601732

              @tmo_mike_c when I send the same message to myself via gmail using, the entire message is delivered successfully.

              • magenta8601732
                • magenta8601732

                  tmo_mike_c @


                  I didn't have to change the language at all for gmail. I'm revisiting this now because I'm experiencing the same issue across other messages.


                  Here is another sample message being generated by our platform and sent to T-Mobile via Twilio which it appears T-Mobile is not handling well:

                  For CREDIT CARD xxxx7834:




                  • Current balance: $0.00



                  • Available Credit: $7,500.00



                  • Credit Limit: $7,500.00


                  Would you like to see recent transactions for this account?


                  This message never got delivered to my device, but Twilio shows 'Delivered' in the 'Carrier Network' Stage of their logs.



                  The same exact message, sent the same exact way, is delivered without issue by AT&T (as one point of comparison).


                  It's worth reinforcing that I am approaching this problem from 2 perspectives:

                  1. As a T-Mobile customer, I want to ensure I am receiving all the messages which are sent to my device.

                  2. As a representative of a business that delivers messages to T-Mobile customers, I want to ensure that delivery status of those messages is reflected accurately... and to understand what steps can be taken on our end to ensure successful delivery.


                  I would really appreciate the opportunity to speak with somebody by phone regarding this issue. As mentioned in my previous post, I opened multiple support tickets when this first occurred and had disappointing interactions / poor follow-through from multiple T-Mobile Experts. I can reproduce in real-time, provide phone numbers, message sIDs, etc... anything to help identify the root cause and work toward a solution.


                  Right now we're re-evaluating OCS2 vs GSM message encoding and the impact that certain characters may have on deliverability via T-Mobile. But it would be great if someone there could provide guidance or knowledge of any known issues.

                    • tmo_mike_c

                      You've been really thorough with your troubleshooting and I appreciate that. I'm bummed this is still going  on, but I agree you'll need to speak with our Tech Care team and revisit those tickets with these new examples. You can Contact Us and call, or you can message our T-Force team through the Facebook and Twitter links. Either way, I'd suggest mentioning those previous tickets and having these examples on standby so they can update the ticket with them.

                        • apin

                          Re: Same SMS messages always fail to be received

                          Has there been any resolution to magenta8601732's issue? I'm having a very similar problem. I work for a company that sends SMS messages to agents via Twilio. Recently, two agents (T-Mobile carrier) reported that they're not receiving our SMS text messages. One of them used to receive our texts (last time she received one was 09/10 8:44am CDT). I used to be able to receive our Twilio SMS too. I ran a Twilio test yesterday and today, sending a message to myself (773-396-7370). Everything on the Twilio end indicates "Delivered." But I (and these two agents) do not receive the SMS messages from Twilio. There is no problem with other carriers.

                          Screen Shot 2019-09-12 at 12.40.41 PM.png

                      • magenta10023599

                        @tmo_mike_c I'm also a Twilio customer and have been experiencing the exact same issues as described by magenta8601732. We would really love to understand if there is any resolution here or any updates that can be provided. These are 1:1 messages delivering specific information (in this case just informing a truck driver about an upcoming delivery), so it's really frustrating to not be able to understand whether the message is delivered or not. Please advise whether there has been any progress here.

                        • apin

                          I think my (company) problem is very similar. Our company sends Twilio SMS texts to clients from a 10-digit phone number. T-Mobile recipients were not receiving SMS text, even though the Twilio log indicated "Delivered". I logged a ticket with Twilio. I also communicated with T-Mobile T-Force via Facebook Messenger. T-Mobile rep AmandaCross was very responsive, and submitted a ticket #24997882 on my behalf (this might be T-Mobile internal --- not something I can look at). Before T-Mobile could give me an explanation, Twilio told me that "Per T-Mobile, All messages from Twilio 1XXXXXXXXXX have been blocked for spam . . ." I told T-Mobile that Twilio said we're blacklisted.


                          My chat with T-Mobile yesterday:


                          T-Mobile: “I heard back from our team again and they were able to adjust the settings here to make sure you can receive messages from Twilio (the number you mentioned above). All that I would ask is if you can test things out and make sure things are 100% working! I will look forward to hearing back from you today and I appreciate you working with me. ^AmandaCross”


                          Me: I still see in Twilio logs that the message is “Delivered” but I don’t receive the SMS.


                          T-Mobile: "Thank you for touching base with us. On this side, all blocks have been removed and you may want to partner with Twilio to have them refresh things on their side as well moving forward. ^AmandaCross”


                          I asked Twilio if there's anything Twilio can do from their end.


                          This morning Twilio asked me:

                          "Please can you send me some example SIDs where you are still not seeing delivery from Twilio?

                          Then I will pass them onto the carrier for investigation."


                          I ran a test Twilio SMS, to my T-Mobile number. It's working this morning. I let Twilio know that it's working for me now.


                          I felt like I was coordinating between Twilio and T-Mobile. Maybe if you contact T-Mobile support, ask them to look at my ticket #24997882 (even though I don't know what they've logged in it).


                          Lastly, just received from Twilio:

                          "I was looking into this issue earlier today, but nothing has yet been changed on our end.


                          Sometimes changes will not be immediate on the providers side, and can take up to 24 hours to come into effect, as there are multiple intermediate carriers that need to be informed of changes to update their routing for the following day.


                          However, I'm glad to hear that it's now working again for you now!


                          Please let me know if you have any further questions or concerns."

                          • magenta10108056

                            We are having the same issue. We do have updated SMS status activated and are getting the messages returned as undelivered. The error from twilio is "(Error: 30007) Carrier violation. Your message content was flagged as going against carrier guidelines." We have not identified the flagged content at this time.

                            • raaz78

                              I have esact same issue. Anybody able to solve it?


                              My message body


                              Trailer - 2156-SN-HI

                              Dropped Trailer - 1956-SN-HI

                              Load -  #00676


                              Stop 1 - Pickup

                              Five Stars Logistics Yard

                              14750 Slover Avenue, Fontana, CA, 92337


                              08:15 AM - 12:15 PM


                              Stop 2 - Delivery

                              Best Buy Distribution Center

                              636 U.S. 90 Alternate, Missouri City, TX, 77489


                              04:00 AM - 04:00 AM

                              delivery# 81452907

                              • magenta9499596

                                Having the same issues with message from Twilio getting blocked by Tmobile. AT&T and Verizon does not have this issues.


                                It's only Tmobile that is blocking/filtering the messages for the last 8-9 months.


                                It appears Tmobile considers these business related commercial SMS messages at spam or something and just blocks them. This is causing a lot of issues for several people that rely on automated message that are sent from business.


                                I sincerely hope Tmobile fixes the problem quickly.

                                • magenta10373823

                                  I am having this same issue, but not with Twilio. I have a Google Voice number and a RingCentral number. I use these in my business. I also have a personal T-Mobile number. Certain SMS messages sent from GV (Google Voice) and RC (RingCentral) to my T-Mobile number do not get delivered. There doesn't seem to be any rhyme or reason on why some do get delivered and others don't. It is not just my phone number, I have sent SMS messages from GV and RC to other T-Mobile numbers and those individuals don't receive those text messages either. This is a real problem because I send SMS from GV and RC in my business and I don't know which carrier my clients are using. This issue apparently started sometime after October 16 because I have SMS test messages on October 16 with no issues. This also is not a GV or RC issue, since SMS messages sent from both platforms exhibit the same problem. This has to be an issue with T-Mobile. I have sent the exact same SMS messages that would not be delivered to a T-Mobile customer to AT&T and Verizon customers and those get delivered without issue. I have not tested Sprint.


                                  For example, the following messages do get delivered (without quotes):

                                  "1234567890 1234567890 123456789"

                                  "Hi, this is [name]"

                                  "Hi, this is Aaron Rogers"


                                  But the following messages do not get delivered (without quotes):

                                  "1234567890 1234567890 1234567890" (adding a zero to the end)

                                  "Hi, this is [INSERTING MY ACTUAL NAME]" <= my actual name is somewhat foreign


                                  The fact that "Hi, this is Aaron Rogers" gets delivered but "Hi, this is [MY ACTUAL NAME]" does not is unbelievable. This issue is not that my actual name has more characters because I tried a variation with a truncated version of my name to match the character count in "Hi, this is Aaron Rogers" and it still did not go through. I'm not going to call it racist at this point, but something very stupid is happening and needs to be fixed sooner than later.

                                    • garudadarkblack

                                      I have a regular T-Mobile number and I send text messages with pictures and links to a few friends and family. A few days before Thanksgiving my multimedia messages stopped sending. It wasn't until Tuesday after Thanksgiving that I learned that none of my texts were going through. I went into the store but they could do nothing. I called tech support and after more than 30 minutes they determined that my messages were flagged as spam and all my messages were being blocked until an investigation could be done. They said they would elevate it and send me an email. Two days later I still heard nothing back so I called again. I was told it would be 10 to 20 (business?) days before the investigation was done and I could text again. That would carry into Christmas. I said that was unacceptable. A tech expert said he would fix the issue and call me back after I restarted my phone. That was over 24 hours ago and I've heard nothing and nothing has changed. Going to drop T-Mobile and switch providers this weekend. They are blocking messages they falsely identify as spam and aren't telling you, then they say it is your fault for sending spam messages. I'm not dealing with this company anymore. Probably won't go to Sprint since a merger seems to still be in the works.