Documentation

The reference for Bulk SMS Sender, the add-in that sends and schedules SMS from Microsoft Excel through your own Twilio account: the exact range contract, what the delivery-status column means, how scheduled sends fire from the cloud, the two custom functions, and every limit in one place.

Overview

Bulk SMS Sender is an add-in for Microsoft Excel that turns a selected range into text messages. The first column holds phone numbers, the second holds message text, and a per-row delivery status is written back into the column immediately right of your selection. It can also schedule a range to go out later from the cloud, and it exposes two custom functions, =SMS.SEND and =SMS.STATUS, for use directly in formulas.

The defining design decision is bring-your-own-Twilio. You connect your own Twilio account once, and every message is sent on that account, from your own sender number, at Twilio's own rates.

Requirements

There is no API key to mint, no webhook to configure and no public URL to expose. Sign-in is email and password only: popup-based OAuth is unreliable inside the Office webviews the add-in runs in, so there is deliberately no single sign-on.

Getting started

The short version, in six steps:

1. Install the add-in and open it from the Home tab of the ribbon.
2. Create an account in the task pane with an email address and a password.
3. Paste your Twilio Account SID, Auth Token and a From number (or MG… Messaging Service SID) into 1 · Twilio setup and save.
4. Run Test my Twilio setup and receive a real test text on your own phone.
5. Select a range (phones in the first column, message text in the second), then preview and send from 2 · Send to selected range.
6. Read the statuses written into the column right of your selection.

The quickstart walks through the same six steps in full, including the sideload instructions per platform and an example of what a good sheet looks like.

Bulk send from a range

Select a range in the sheet, choose Preview selected range, check what the preview reports, then send. Messages go out one row at a time, with a running counter, and the pane finishes with Done: N sent. Statuses written next to your selection.

The column contract

Only two columns are read, and their meaning is fixed:

One row is one recipient, and each row carries its own message text, so every message can be different. Selecting fewer than two columns is refused outright with "Select at least two columns: phone numbers in the first, message text in the second."

Phone-number normalisation

Before a number is validated, spaces, hyphens, brackets and dots are stripped, and a leading 00 is converted to +. What must remain is E.164: a +, a non-zero first digit, and 7 to 15 digits in total.

Header-row detection

The first row of the selection is skipped as a header only when all of the following hold: the selection has more than one row, the first cell is not a valid phone number, it is not empty, and it contains at least one letter. The pane then says "First row looks like a header and was skipped."

What makes a row invalid

Bad rows are flagged, never silently dropped. Each one gets its own reason, shown in the preview and written into the status column:

The preview reports Selection <address>: N message(s) ready., then the first five problem rows, then …and X more rows with problems. If nothing is sendable you get "Nothing sendable in this selection."

Delivery-status writeback

Statuses are written into the column immediately right of the entire selection, on the same sheet, aligned row for row. Select A1:B50 and they land in C; select A1:D50 and they land in E. A skipped header row and completely blank rows get no cell written at all.

If the send succeeded but the sheet could not be written, the pane says Done: N sent, but writing statuses to the sheet failed. The messages were still sent; only the writeback failed.

Scheduled sends

Scheduling is a paid feature. It takes the same selected range and a date and time, stores it, and sends it from the cloud when the moment arrives, with Excel closed and your computer off. On a free plan the attempt is refused with "Scheduled sends are a paid feature. Upgrade to schedule messages."

Creating a schedule

Select the range, pick a date and time under 3 · Schedule, and choose Schedule selected range. The same parser runs, so invalid rows are reported and left out, and the confirmation tells you how many were scheduled and how many were skipped.

How a schedule fires

A worker runs every minute in the cloud and claims schedules that are due, one at a time and transactionally, so overlapping runs can never double-send. Each run has a self-imposed sending budget; if a very large batch reaches the end of it, the remaining rows are closed out honestly with Not sent: the sending window closed before this row was reached. Re-send these rows from the sheet. rather than being left in limbo.

Cancelling

Up to 50 schedules are listed, ordered by send time with the latest first. A Cancel button appears while a schedule is still pending. Once the worker has claimed it the cancel is refused, with "Schedule is already processing and can no longer be canceled." That is deliberate: by then the messages are already going out, and reporting a successful cancel would be a lie.

Writing statuses to the sheet afterwards

A finished schedule shows a Write statuses to sheet button when it still knows which sheet and range it came from. It writes <status> · <sid>, or error: <message> for rows that failed, into the same column right of the original range.

Custom functions

Two custom functions are available in the SMS namespace. They run in the same shared runtime as the task pane and reuse its sign-in, so the task pane must have been opened and signed in for them to work. Otherwise the cell reads "Sign in first: open the Bulk SMS Sender task pane (Home ribbon) and log in."

SMS.SEND: send one message

SMS.STATUS: look up a delivery status

Test my Twilio setup

The validator in 1 · Twilio setup runs four checks in order and stops at the first failure, so you get one specific thing to fix instead of a wall of errors. It needs your own mobile number in E.164 format, because the last check sends a real message to it.

Credential format is checked earlier still, at save time and before Twilio is contacted at all, so a mistyped SID is caught immediately: the Account SID must be AC plus 32 hex characters, the Auth Token must be at least 32 characters, and From must be E.164 or an MG… Messaging Service SID.

Plans & the free cap

How the cap behaves

• The month is a UTC calendar month; the counter resets at the start of each one.
• Quota is checked before each message is handed to Twilio and counted once Twilio accepts it, so a row Twilio rejects costs you nothing. A message Twilio accepts and the carrier later fails to deliver has already been counted, as it has by Twilio. A burst of simultaneous sends can overshoot the cap very slightly, which is a deliberate trade-off against reserving quota for sends that may never happen.
• Test sends and duplicate-suppressed sends are not counted.
• When a bulk send trips the cap, the row that hits it is written as error: Monthly free limit of 25 messages reached. Upgrade to send unlimited messages. and every remaining row is written as skipped: free limit reached without further calls to Twilio. An upgrade button appears inline.
• In a =SMS.SEND cell, the same message appears as the cell's error.

Limits & what it does not do

Hard limits

Deliberately out of scope

Bulk SMS Sender is send-only by design. That shapes several things it does not do:

• No inbound SMS and no reply handling. Replies arrive on your Twilio number and are visible in your Twilio console. The add-in never reads them.
• No STOP or opt-out management. That stays on your own Twilio number, which is where carriers require it to live, and Twilio's own opt-out handling continues to apply. A recipient who has opted out produces Twilio error 21610: The recipient has unsubscribed. on the row that tried to reach them.
• No contact management or CRM. Your list lives in the spreadsheet, which is the point.
• No mobile support. Excel on Windows, Mac and the web only.
• No message templating or mail-merge syntax. Build the per-row text with ordinary Excel formulas such as CONCAT or TEXTJOIN, then send the resulting column.

Troubleshooting

Most problems are Twilio configuration rather than the add-in. Run Test my Twilio setup first: it stops at the first failure and names the fix. The messages below are the ones the add-in actually shows.

"Select at least two columns: phone numbers in the first, message text in the second."

Your selection is one column wide. Select the phone column and the message column together, for example A1:B50.

"… is missing its country code. Use E.164 like +4520304050."

The number has no country code. This usually happens when Excel has stored the number as a plain number and dropped the leading +. Format the column as Text and re-enter it, or write the number with a leading + or 00.

"Could not read the selection. Click a range in the sheet first."

Nothing is selected in the workbook, or focus never left the task pane. Click a range in the grid and preview again.

"Connect your Twilio account first…"

No credentials are saved for this account. Fill in Account SID, Auth Token and From in 1 · Twilio setup and save. During a bulk send this also stops the rest of the batch, since nothing else would succeed either.

"Twilio rejected the Account SID or Auth Token (HTTP 401)."

Copy both values again from the Account Info panel of the Twilio Console dashboard. The Auth Token is hidden behind a "show" toggle, and a partial copy is the usual cause. The saved-credentials version of the same problem reads "Your saved Twilio credentials were rejected (HTTP 401). Re-enter your Account SID and Auth Token in Settings."

"This Twilio account does not own +1555…"

The From value must be a number you bought or verified in that same Twilio account (Phone Numbers → Manage → Active numbers), or a Messaging Service SID starting with MG. The error lists up to three numbers the account does own.

Your Twilio account status is not "active"

Twilio has suspended or closed the account, usually for billing. Resolve it in the Twilio Console; nothing can be sent until the status is active.

Twilio error 21608

Your Twilio account is on trial and may only text verified numbers. Verify the recipient in the Twilio Console, or upgrade the Twilio account. This is Twilio's restriction, not ours.

Messages stay on "queued"

That is the creation-time status and it never updates by itself. Recalculate =SMS.STATUS(sid) against the SID for the live state.

If Twilio itself keeps the message queued or reports it as filtered, the cause is usually on the route: US long-code traffic without A2P 10DLC registration is commonly filtered by carriers. Register your brand and campaign in the Twilio Console.

A row says duplicate of SM…

That exact recipient and body already went out within the previous 60 seconds, so it was not sent a second time and your quota was not charged. If the repeat was intentional, wait a minute or change the text.

"Monthly free limit of 25 messages reached."

The free allowance for this UTC calendar month is used up. It resets at the start of the next month, and upgrading removes the cap and unlocks scheduled sends.

"Schedule is already processing and can no longer be canceled."

The per-minute worker has already claimed that schedule and its messages are going out. Cancelling is only possible while a schedule is still pending.

A cell says "Sign in first: open the Bulk SMS Sender task pane (Home ribbon) and log in."

The custom functions reuse the task pane's session. Open the pane from the Home tab, sign in, then recalculate.

#NAME? in a cell

The add-in is not loaded, so Excel does not recognise the function. Open the task pane once, then recalculate with Ctrl+Alt+F9 (Cmd+Alt+F9 on Mac).

The task pane opens but stays blank

Close and reopen it first. If it persists, write in and say which Excel you are on: Excel on the web loads the add-in from a regional Office origin, and that has been the source of this before.

Sign-in problems

The pane reports these plainly: "Wrong email or password.", "An account with that email already exists. Sign in instead.", "Password must be at least 6 characters.", "Too many attempts. Wait a minute and try again." and "Network error. Check your connection." Use Forgot password? to get a reset email.

FAQ

Support

See also the privacy policy for exactly what is stored and where, and the terms of use for acceptable use and billing.