Quick answer: Twilio runs a Heightened Awareness Period from 19 November 2026 to 4 January 2027, during which US send rates are monitored and may be limited at account level. The fix is calendar work: finish registration by late September, then prove your required send rate fits the tier you actually hold.
How do I stop my SMS throughput being throttled over the Black Friday and holiday period?
You do not stop it in November. US messaging throughput is assigned in advance — by number type, by campaign use case and, for A2P 10DLC Standard Brands, by a Trust Score that The Campaign Registry assigns during registration — and every mechanism for changing those assignments takes weeks, not hours. By the time your texts are visibly slow, the only levers left are the shape of the send and the size of the window.
So the work is front-loaded, and there is a published date to work back from. Twilio announced on 17 September 2026 that it will run a Heightened Awareness Period (HAP) from Thursday 19 November 2026 to Monday 4 January 2027. That is a real, published operational window, not a marketing deadline, and it is the only deadline on this page.
Day one, today: open Trust Hub, select each US A2P brand, and read the TCR Trust Score detail. Write down, for every US sender you own, four numbers: the number type, the campaign use case, the allotted messages per second, and the T-Mobile daily cap. Teams often find that nobody can name all four from memory. Finish state for day one: a one-page sender inventory in which no cell reads “unknown”.
What Twilio’s Heightened Awareness Period actually says
The changelog entry, quoted from Twilio’s changelog (read 22 September 2026):
Between Thursday, November 19, 2026 and Monday, January 4 2027, Twilio will enter a Heightened Awareness Period (HAP) to help ensure reliable message delivery during peak traffic times, such as Black Friday and Cyber Monday. During this period, message sending rates to U.S. destinations will be monitored and may be limited at the account level for toll-free, short code, and 10DLC numbers. Accounts that send high volumes of messages from short codes or toll-free numbers may be temporarily migrated to Market Throughput during the HAP. Customers will be notified via email if their account is affected. Market Throughput doesn’t affect 10DLC numbers, which will continue to live on Account Based Throughput.
Three things follow from that wording, and they are easy to miss on a fast read. The limiting is at the account level, not per number, so buying more numbers is not a workaround. The temporary migration applies only to short code and toll-free senders. And 10DLC — the number type most AI SMS agents actually run on — is explicitly excluded from that migration and stays on Account Based Throughput throughout.
Account Based Throughput vs Market Throughput: what a temporary migration means
These are two different places to put the ceiling, and Twilio documents both. Under Account Based Throughput the ceiling sits on your parent account per sender type and channel. Under Market Throughput it sits on your parent account per country and per destination carrier.
| Account Based Throughput | Market Throughput | |
|---|---|---|
| Where the limit sits | Parent account, per sender type (short code, toll-free) and per channel (SMS, MMS) | Parent account, per country, then per destination carrier or sender type |
| How the number is set | Twilio configures it from your historical peak send times | You forecast volumes per country with your account owner; Twilio Support reviews and approves the MPS |
| Applies to US 10DLC SMS/MMS? | Yes — it acts as a ceiling on your collective A2P traffic | No. Twilio’s docs state Market Throughput cannot be used for US 10DLC SMS and MMS, which is serviced with A2P campaign throughput |
| Congestion behaviour | One queue per channel-and-sender combination; a busy network shares the account ceiling with the quiet ones | Traffic is separated by destination carrier, so congestion on one network does not delay traffic to the others |
| Work required from you to migrate | — | None to your integration. Twilio Support configures the values and migrates existing traffic during off-peak hours |
Read practically: a temporary migration to Market Throughput is a change of accounting unit, not a punishment. Your capacity stops being expressed per short code or per toll-free number and starts being expressed per destination carrier at account level. The planning consequence is that your sending model has to be able to answer “how many segments per second are we pushing at Verizon specifically”, and most send schedulers cannot.
The eight-week countdown to 19 November 2026
This is the first of the two tables on this page you can lift straight into a plan. Every row has a real date, one concrete action and a finish state you can test. The dates are counted back from 19 November 2026 in whole weeks; the durations behind them are Twilio’s own published review windows, listed in the source table at the end.
The arithmetic that sets the first row is worth doing out loud. Twilio publishes the following chain for a Direct Standard registration: Customer Profile approval may take 72 hours or more; a Brand in IN_REVIEW is under manual third-party review and “manual reviews take seven business days or more”; and a submitted Campaign “undergoes a manual vetting process… This process can take between two to three weeks to complete.” Chain those durations end to end from 24 September, at their longest stated value, and you land around 29 October. Two of the three are floors rather than ceilings — Twilio writes 72 hours or more and seven business days or more — so treat 29 October as the earliest good outcome, not the worst case — three weeks clear of the window, with no resubmission. Start in mid-October instead and you have no slack at all.
| Milestone | Real date | Action | Finish state |
|---|---|---|---|
| T−8 weeks | Thursday 24 September 2026 | Inventory every US sender in Trust Hub, then file anything unregistered or under-tiered on the same day. Standard Brand registration includes secondary vetting (US$41.50, US$46 total) and is what produces a Trust Score at all; a Low Volume Standard Brand skips it. | The sender inventory exists with a number in every cell, and every new Customer Profile, Brand and Campaign has been submitted. Nothing is waiting on you. |
| T−6 weeks | Thursday 8 October 2026 | Submit toll-free verification for every toll-free sender (Twilio asks for approximately 3–5 business days to process) and chase anything still showing IN_REVIEW. If a toll-free verification is rejected, resubmit inside seven days to keep priority review. Twilio publishes two start points for that clock, so work to the earlier: its API onboarding guide sets edit_expiration seven days from the initial request, while error 30437 counts seven days from the rejection. |
Every toll-free number is Pending or Approved, and every rejection has been corrected inside its seven-day window rather than resubmitted cold. |
| T−4 weeks | Thursday 22 October 2026 | Run the peak-window MPS check below against your actual November list and your actual send window. Where required MPS exceeds allotted MPS, widen the window, split the send across days, or raise the tier now while there is still time for a review. | A written send plan in which required MPS is less than or equal to allotted MPS for every scheduled send. |
| T−2 weeks | Thursday 5 November 2026 | Text STOP, START and HELP to every sender from a real handset, and set a deliberate Validity Period on every time-sensitive send. The default and maximum is 36,000 seconds (10 hours), which is long enough for a queued Black Friday offer to arrive on Saturday morning. | Opt-out, opt-in and help confirmed on every sender, and no time-sensitive template still running on the 10-hour default. |
| The window | Thursday 19 November 2026 to Monday 4 January 2027 (46 days) | Watch for the email — Twilio says customers will be notified if their account is affected. Monitor queue depth daily in Messaging Insights. Do not file a new campaign expecting it to clear before Black Friday (27 November) or Cyber Monday (30 November). | A named person checks queue depth every day of the window, and no new registration has been filed against a November deadline. |
| After | From Tuesday 5 January 2027 | If you were migrated to Market Throughput, confirm with your Twilio account team whether that has been reversed. Record actual peak segments per second and actual peak daily volume per carrier. | Measured peak numbers are written into the 2027 plan, so next year’s T−8 starts from measurement rather than memory. |
The peak-window MPS check: 40,000 messages into a four-hour window
The second is a worked calculation with every input shown, so you can substitute your own numbers. It answers the question the countdown cannot, which is whether your November send physically fits.
Inputs. A list of 40,000 US recipients, one message each. A message body of 172 GSM-7 characters. A send window of four hours, from 9am to 1pm on Black Friday.
Step 1 — convert messages to segments. Throughput is measured in message segments per second, not messages per second. Twilio documents 160 GSM-7 characters for a single-segment message and 153 characters per segment once a message is concatenated, because seven characters of each segment are consumed by the User Data Header. A 172-character body therefore ships as 2 segments: 40,000 × 2 = 80,000 segments.
Step 2 — convert the window to seconds. 4 hours × 60 minutes × 60 seconds = 14,400 seconds.
Step 3 — divide. 80,000 segments ÷ 14,400 seconds = 5.56 segments per second required.
Step 4 — compare against your allotted tier. The allotted figures below are Twilio’s published total SMS MPS toward the major US networks, by Trust Score band and campaign type.
| Your allotted MPS | Who gets it | Time to clear 80,000 segments | Fits a four-hour window? |
|---|---|---|---|
| 225 | Standard Brand, Trust Score 75–100 | 355.6 s = 5 min 56 s | Yes, with 3h 54m spare |
| 120 | Standard Brand, Trust Score 50–74 | 666.7 s = 11 min 7 s | Yes, with 3h 49m spare |
| 12 | Standard Brand, Trust Score 1–49, or a Low Volume Standard Brand that skipped secondary vetting | 6,666.7 s = 1 h 51 min 7 s | Yes, with 2h 9m spare |
| 3.75 | Low Volume Mixed campaign, regardless of Trust Score | 21,333.3 s = 5 h 55 min 33 s | No. The last message lands 1 h 55 min 33 s after the window closes |
| 2.25 | Sole Proprietor Brand (also limited to 1 campaign, 1 number and 1,000 segments a day to T-Mobile, so this send is impossible for a second reason). Twilio’s prose on the same page says 1 MPS while its table totals 2.25; we use the table | 35,555.6 s = 9 h 52 min 36 s | No. It survives the 10-hour queue ceiling with only 7 min 24 s to spare |
What actually happens when required MPS exceeds allotted MPS. The messages are not rejected and they are not dropped. Twilio queues them: “Messages will begin to queue if you send message requests faster than your account-based MPS… Messages will persist in the queue for a maximum of 10 hours.” Past that they fail with error 30001, Queue overflow. So the business consequence of under-provisioned throughput is almost never a delivery failure — it is a time-sensitive send landing late. A four-hour flash offer whose last message arrives at 2:55pm has not failed any technical check. It has simply been read after the sale closed.
One more input worth testing, because it is the one an AI agent moves without telling you. If a single character in that 172-character body forces UCS-2 encoding — a curly apostrophe, an em dash, an emoji — the per-segment limit drops from 153 to 67 and the same body becomes 3 segments, not 2. Required MPS goes from 5.56 to 8.33, a 50% increase, from one invisible character. At 2.25 MPS that send would need 14 h 48 min and would time out of the queue entirely.
The two-ceiling check: per second and per day come from different tables
Here is the part most peak-season planning misses, and it is the decision rule worth taking away from this page. A US send is governed by two independent ceilings, and they are published in two separate Twilio tables with two different sets of Trust Score bands. Passing one tells you nothing about the other.
The per-second table bands Trust Scores as 75–100, 50–74 and 1–49. The T-Mobile daily-cap table bands the same scores as 75–100, 50–74, 25–49 and 1–24. The merged view below is ours; each half traces to the Twilio article named in the source table. We published the daily-cap bands on their own in the 10DLC cost breakdown; what is new here is that the two tables do not cut the Trust Score range at the same place.
| Trust Score | Ceiling 1: total SMS MPS toward major US networks | Ceiling 2: T-Mobile daily cap, outbound SMS segments + MMS, per EIN |
|---|---|---|
| 75–100 | 225 | 200,000 per day |
| 50–74 | 120 | 40,000 per day |
| 25–49 | 12 | 10,000 per day |
| 1–24 | 12 | 2,000 per day |
| Low Volume Standard Brand, secondary vetting skipped | 12 | 200,000 per day if a Russell 3000 index company, otherwise 2,000 per day |
| Sole Proprietor Brand | 2.25 total (0.25 to AT&T, 1 per number to T-Mobile, 1 per number to Verizon) | 1,000 per day |
Two brands at Trust Score 30 and Trust Score 20 get the identical 12 MPS and a five-fold difference in daily headroom — 10,000 against 2,000. Run the same 40,000-recipient send from the example above with 40% of the list on T-Mobile and you are pushing 32,000 segments at T-Mobile in one day: inside the cap at Trust Score 50 or above, though 32,000 of a 40,000 allowance leaves little for anything else that day, and stopped with error 30023 after the first 10,000 at Trust Score 30. The cap is applied at brand level per EIN and is shared across every registration under that EIN, including registrations you hold with a different provider. It resets at midnight US Pacific time.
There is a third ceiling above both, and it is the one the HAP notice is actually about: the account-based rate limit. Twilio’s own worked example is blunt about it — an account limited to 100 MPS with three approved campaigns at 75 MPS each is still limited to 100 MPS combined, and “each message segment that exceeds that 100 per second will be placed in queue.”
Where an AI SMS agent hits this differently from a bulk blast
A blast is one outbound segment per recipient, scheduled once. A two-way AI agent is a different traffic shape, and three of its properties interact with throughput planning.
Inbound arrives whenever the human feels like replying. A blast that goes out at 9am produces a reply curve that peaks somewhere in the following hour and then runs for days. Your agent’s responses to those replies are outbound traffic competing for the same account-level ceiling as the next scheduled campaign. If you are planning capacity for November, plan the reply tail, not just the send. The economics of that tail are covered separately in our breakdown of what a two-way 10DLC conversation costs per segment, which prices inbound as well as outbound.
Generated text has an unstable segment count. A hand-written template is measured once. A model that writes each message fresh will, sooner or later, emit a smart quote or an en dash and silently push that message from two segments to three, as shown in the calculation above. Normalise generated copy to the GSM-7 character set on the way out and your required MPS stops moving on its own. Twilio Smart Encoding will substitute some of these characters for you — it covers curly quotation marks but not emoji — so it narrows the problem rather than removing it. This is also why sample messages filed at registration should come out of the live generator rather than being written by hand — a mismatch there is one of the more common rejection causes, which we cover in why 10DLC campaigns get rejected and how to resubmit inside the window.
Opt-out has to keep working while everything else is queued. On toll-free senders this is mostly out of your hands in a useful way: Twilio documents that toll-free numbers carry “a layer of opt-out handling outside of Twilio that cannot be removed or customized”, so a STOP reply is honoured at network level regardless of what your queue is doing. On long codes, Twilio handles STOP, UNSUBSCRIBE, END, QUIT, STOPALL, REVOKE, OPTOUT and CANCEL by default. The risk is the agent layer, not the carrier layer: if your agent enqueues its own confirmation or its own follow-up behind a 40,000-message backlog, the person who asked to stop hears nothing for hours. Route opt-out acknowledgements outside the bulk queue, and test that on 5 November rather than on 27 November. Where a single agent runs SMS alongside voice or email, the pacing question is a scheduling question too, which is the subject of our multi-channel outreach orchestration playbook.
If you are sending from Australia into Australian handsets, none of the US carrier machinery above applies, but a separate registration does — see Australia’s mandatory SMS Sender ID Register and what it means for AI outreach. Twilio’s HAP notice is scoped to US destinations only.
Frequently asked questions
Why are my texts slow in November?
Most often because your required segments per second exceeds the rate your campaign is allotted, so the overflow sits in a queue rather than failing. Twilio states that messages persist in that queue for a maximum of 10 hours before failing with error 30001. Between 19 November 2026 and 4 January 2027 there is a second reason: Twilio has published that US send rates are monitored and may be limited at the account level during its Heightened Awareness Period.
What is a Heightened Awareness Period and does it apply to me?
It is a defined window in which a provider watches US traffic more closely to protect delivery during peak demand. Twilio has published one running from Thursday 19 November 2026 to Monday 4 January 2027, covering toll-free, short code and 10DLC numbers sending to US destinations. Twilio says affected customers are notified by email, and that high-volume short code and toll-free accounts may be temporarily migrated to Market Throughput for the duration.
Will my 10DLC numbers be moved to Market Throughput?
No. Twilio’s changelog entry states that Market Throughput does not affect 10DLC numbers, which continue to live on Account Based Throughput. Twilio’s Market Throughput Overview gives the underlying reason: Market Throughput cannot be used for US 10DLC SMS and MMS, because that traffic is serviced with A2P campaign throughput at rate limits permitted by the destination carriers.
How long does it take to raise my 10DLC throughput?
Longer than a fortnight, and Twilio publishes more than one current figure, so plan against the longest. Its Direct Standard onboarding guide says campaign reviews are currently taking 10 to 15 days and that manual campaign vetting can take between two and three weeks; its throughput and Trust Scores support article, updated 9 September 2026, says campaign reviews are currently taking 5 to 10 days. Brand manual review is published at seven business days or more, and Customer Profile approval at 72 hours or more. Chain the maximums and a cold start is roughly five weeks before any resubmission.
How long does toll-free verification take?
Twilio asks for approximately 3 to 5 business days to review and process a toll-free verification submission. If it is rejected and eligible for resubmission, the priority window is seven days, and Twilio publishes two readings of when it starts: the API onboarding guide sets the edit_expiration timestamp seven days from the initial request, while error 30437 counts seven days from the rejection. Work to the earlier. After it closes the number stays restricted until you resubmit, and error 30437 states the late resubmission is processed in the standard queue instead of the priority queue.
Can I just buy more numbers to get more throughput?
Not under account-level throughput, which is the point of the model. Twilio documents that under Account Based Throughput your capacity is set at the parent account level and all numbers share it, and that under the older per-number model “purchasing more phone numbers won’t necessarily increase the customer’s total throughput during congested sending times.” On toll-free specifically, Twilio also warns against using multiple toll-free numbers for the same use case purely to gain MPS, because carriers do not consider that acceptable without a business reason.
Does throttling affect STOP and HELP replies?
Carrier-level opt-out on toll-free numbers is handled outside Twilio and cannot be removed or customised, so a STOP reply is honoured whatever your queue depth. What can be delayed is anything your own agent sends in response. The CTIA Messaging Principles and Best Practices (May 2023) states that message senders should ensure consumers have the ability to opt out at any time, should support multiple opt-out mechanisms including phone, email and text, and should send one final opt-out confirmation per campaign with no further messages after it. That confirmation is the one to route around your bulk queue.
What should I do if I have not registered anything yet and it is already October?
File immediately and plan on the window rather than through it. Register the brand first, then the campaign, then the numbers, because a campaign filed against an unapproved brand simply fails again. Accept that a cold registration started in late October is unlikely to be sending at full tier before Black Friday on 27 November 2026, and schedule the November programme at whatever throughput you actually hold, with a longer send window instead of a bigger one.
Where every figure on this page comes from
| Figure | Who published it | Link | Date read |
|---|---|---|---|
| Heightened Awareness Period, 19 November 2026 to 4 January 2027; account-level limiting; temporary migration to Market Throughput; 10DLC stays on Account Based Throughput | Twilio | Twilio changelog, 17 September 2026 | 22 September 2026 |
| Short code sender throughput of 100 MPS; Market Throughput cannot be used for US 10DLC SMS and MMS; onboarding is Forecast, Review, Configuration and Migration during off-peak hours; purchasing more phone numbers will not necessarily increase total throughput during congested sending times | Twilio | Market Throughput Overview | 22 September 2026 |
| Account-level rate limits set from historical peak send times; queues per channel and sender; 10-hour maximum queue persistence; account limit acts as a ceiling over A2P campaign throughput | Twilio | Account Based Throughput Overview | 22 September 2026 |
| Error 30001 Queue overflow; Validity Period default and maximum of 36,000 seconds (10 hours) | Twilio | Error 30001: Queue overflow | 22 September 2026 |
| Trust Score 0 to 100 assigned by The Campaign Registry at secondary vetting; total SMS MPS of 225, 120, 12 and 3.75 by band and campaign type; Sole Proprietor 2.25 MPS, 1 campaign, 1 number, 1,000/day T-Mobile, 15 msg/minute AT&T; toll-free default 3 MPS; account ceiling worked example; campaign reviews currently 5 to 10 days | Twilio | Message throughput (MPS) and Trust Scores for A2P 10DLC in the US (updated 9 September 2026) | 22 September 2026 |
| T-Mobile daily caps of 200,000, 40,000, 10,000 and 2,000 by Trust Score; Low Volume Standard 200,000 or 2,000; Sole Proprietor 1,000; error 30023; brand-level per-EIN application; midnight US Pacific reset | Twilio | T-Mobile Daily Message Limits for Long Code Messaging with A2P 10DLC (updated 18 June 2026) | 22 September 2026 |
| Customer Profile 72 hours or more; Brand IN_REVIEW manual review seven business days or more; campaign reviews currently 10 to 15 days; campaign manual vetting two to three weeks | Twilio | Direct Standard and Low-Volume Standard registration | 22 September 2026 |
| Secondary vetting US$41.50, US$46 total to register a Standard Brand; Low Volume Standard is a Standard Brand that skipped secondary vetting | Twilio | What Is Secondary Vetting for A2P 10DLC? | 22 September 2026 |
| Toll-free verification processing of approximately 3 to 5 business days; higher-throughput toll-free available above the standard 3 MPS | Twilio | Toll-Free Message Verification for US/Canada (updated 1 June 2026) | 22 September 2026 |
| Toll-free default 3 MPS to US and Canada; carriers do not accept multiple toll-free numbers for the same use case purely for throughput | Twilio | Toll-Free SMS and MMS messaging throughput (MPS) (updated 13 March 2026) | 22 September 2026 |
| Seven-day priority resubmission window after a toll-free verification rejection; two published start points; late resubmission processed in the standard queue | Twilio | Toll-Free Verification API Onboarding Guide, Error 30437: toll-free verification edit window expired and Console Onboarding Guide | 22 September 2026 |
| GSM-7 limits of 160 characters single-segment and 153 per concatenated segment; UCS-2 limits of 70 and 67 | Twilio | What is the SMS character limit? | 22 September 2026 |
| Toll-free opt-out handling sits outside Twilio and cannot be removed or customised; long-code default keywords STOP, UNSUBSCRIBE, END, QUIT, STOPALL, REVOKE, OPTOUT, CANCEL | Twilio | Opt-out keyword handling for Toll-Free SMS and Advanced Opt-Out | 22 September 2026 |
| Opt-out guidance: ability to opt out at any time, multiple opt-out mechanisms, one final confirmation message per campaign | CTIA | Messaging Principles and Best Practices, May 2023, section 5.1.3 | 22 September 2026 |
| US Thanksgiving Day falls on Thursday 26 November 2026, from which Black Friday (27 November) and Cyber Monday (30 November) follow | US Office of Personnel Management | 2026 federal holiday schedule | 22 September 2026 |
| Required MPS of 5.56 and 8.33; clearance times of 5 min 56 s, 11 min 7 s, 1 h 51 min 7 s, 5 h 55 min 33 s and 9 h 52 min 36 s | Zian AI | Calculated on this page from the Twilio figures above; every input is shown so the arithmetic can be redone | 22 September 2026 |
What this means if you run an AI SMS agent
Nothing on this page is exotic. It is a sender inventory, a division sum and a calendar, and a competent operator can run all three by hand in an afternoon. What it costs to run is attention at the wrong time of year: the inventory has to be redone every time a campaign or number changes, the MPS check has to be redone every time the list or the window changes, and the segment count has to be re-measured every time the generated copy changes, which for a live AI agent is continuously. That is the part that does not scale by hand.
Zian AI runs autonomous SMS, phone, email and WhatsApp agents, with SmartReach AI™ orchestrating message, channel and timing, and PrecisionPitch AI™ split-testing the scripts underneath. Pacing a send inside a throughput ceiling is a scheduling problem before it is a copy problem, and it is the same problem whether the ceiling is a carrier’s or a calendar’s. Zian AI is in partnership-application beta.