Your Black Friday SMS Throughput Is Locked In October, Not November

September 23, 2026. Twilio has scheduled two Heightened Awareness Periods for the end of this year, and published the deadline ladder that goes with them. A Heightened Awareness Period, or HAP, is a window in which Twilio monitors and manages message throughput to United States destinations across toll free numbers, short codes, 10DLC numbers and RCS senders. The detail that catches e commerce operators every year is that the windows run in November and December, and every deadline that decides how fast you are allowed to send falls in October.

The two windows and what changes inside them

1. United States Midterm Elections HAP: November 2 to November 4, 2026.
2. Black Friday, Cyber Monday and Holiday Peak Season HAP: November 19, 2026 to January 4, 2027.
3. During both windows, short code and toll free traffic for high volume senders temporarily shifts to Market Throughput, under which traffic flows within broader network capacity rather than a per account rate, unless you hold contracted limits.
4. 10DLC numbers stay on Account Based Throughput. RCS senders run on standard per sender limits. Any contracted limits on the account are honoured throughout both windows.
5. Twilio's changelog entry adds that sending rates to United States destinations will be monitored and may be limited at the account level for toll free, short code and 10DLC numbers, and that affected accounts are notified by email. Accounts that get no email keep sending normally.
6. Affected accounts return to their standard pre HAP limits after each window, at 8 AM Pacific on January 4, 2027 for the holiday period.

The deadline calendar

Twilio publishes six dates, and capacity is first come, first served.

1. October 1: submit new RCS senders for carrier approval, and, if you send election traffic, reach out to your account team to review volume forecasts. Twilio says carrier reviews take 4 to 8 weeks.
2. October 16: return your supplementary order form for the elections window.
3. October 26: finalise all throughput locks for the elections window.
4. October 31: review your holiday throughput needs with your account team.
5. November 2: submit any request for extra A2P 10DLC capacity.
6. November 13: sign your supplementary order form to lock guaranteed throughput across short code, toll free and RCS traffic.

Read the RCS line twice. A carrier review of 4 to 8 weeks started on October 1 lands between late October and late November, which means an RCS sender submitted in November will not be approved in time to send anything on Black Friday. There is a Fast Track process to ask about, but the planning assumption should be that November is too late.

What it means for operators

Most senders genuinely do not need to do anything, and Twilio says so plainly: if you do not receive an email, you keep sending normally. The risk is concentrated in a specific profile, and it is a common one for the e commerce brands and agencies we work with.

If a store's entire peak season revenue plan depends on a small number of large abandoned cart and promotional sends on four or five specific days, then throughput is not a technical detail, it is the campaign. A send that queues behind carrier traffic for two hours on Black Friday morning arrives after the discount window the copy promised. The failure mode is not a bounce or an error code, it is a slow send, which is why it rarely gets caught in testing.

Note also what the shift to Market Throughput does to your mental model. On Account Based Throughput you have a number, and you can plan against it. Under Market Throughput your traffic flows within broader network capacity, so the number you were planning against is not the number you have. If your peak plan needs a guaranteed rate, a contracted limit is the only thing that gives you one, and the form that creates it has to be signed by November 13.

How to use this

Do the arithmetic before October 31. Take your largest planned single send, divide the recipient count by the number of minutes you are willing to let the send take, and convert to message segments per second. Compare that to what your account actually sustains today. If the required rate is higher than the observed rate, you have a conversation to have with your account team, and roughly five weeks to have it.

Then check the ground underneath the rate. A brand that is throttled by its own trust score tier will not be rescued by a throughput contract, and that cap is attached to the EIN rather than the platform, as we set out in the 10DLC daily message limit explainer. A campaign that is still pending carrier vetting has a different problem again, covered in why 10DLC campaigns get rejected. And if the peak send includes any automated calling alongside the texts, the consent rules do not relax for the holidays, which is the whole subject of TCPA compliant AI calling.

Sources: Twilio blog, Twilio's 2026 Heightened Awareness Period: Ensuring Reliable Messaging for Peak Season, September 17, 2026, cross checked against the Twilio messaging changelog entry for the November 19, 2026 to January 4, 2027 window and Twilio's Account Based Throughput and Market Throughput documentation.