Bulk SMS Sending: How It Works and How to Start

Bulk SMS sending means delivering the same text, or a personalised version of it, to many recipients in one job instead of one at a time. A bulk SMS sender takes your contact list and message, splits long texts into parts, and passes them to carriers. Message length decides how many parts each recipient gets.

What bulk SMS sending means

Bulk SMS sending is the delivery of one message, or one template, to a list of phone numbers in a single job. Recipients see an ordinary text. The difference is on the sending side, where a list, a queue and a status report replace a phone keyboard.

Bulk SMS vs a single SMS

A single SMS goes from one phone to one number. Bulk sending adds a contact list, merge fields such as a first name, and a queue that tracks each message. The message format does not change, so the same 140-byte limit applies to every recipient. A group chat in a messaging app is different: bulk sending delivers a separate message to each number.

Who uses bulk SMS sending

Clinics send appointment reminders, shops send order updates, schools send closure notices, and event teams send schedule changes. Marketers send offers to customers who opted in. Consent matters more than list size: send only to people who agreed to hear from you, and check the rules in your country, because this guide is not legal advice. For related fundamentals, see more SMS basics guides.

How a bulk SMS sender processes your list

A bulk SMS sender reads your list, builds each message, checks its length and hands it to a carrier connection. In order, it does five things:

1. Reads the numbers and rejects malformed ones.

2. Merges each row's details into the template.

3. Picks an encoding, GSM-7 or Unicode.

4. Splits the message into parts if it is too long.

5. Queues the parts and records a status for each recipient.

Status reports depend on the network, so a "submitted" status does not always mean the phone received the text.

Message formatting and character limits

One SMS is 140 bytes, which holds 160 GSM-7 characters or 70 UCS-2 (Unicode) characters. Longer messages are sent as multipart, or concatenated, messages. Each part carries a small header, so a part holds 153 GSM-7 or 67 Unicode characters. The recipient's phone joins the parts into one message. The limits come from 3GPP TS 23.038 and TS 23.040 (alphabet, message format).

Some GSM-7 characters, such as { } [ ] \ ^ ~ | and €, take two character slots. Run your draft through the counter to check your message length and character count, or read the full guide to SMS character limits.

Why Urdu text or emoji increases message count

Urdu letters, emoji and "smart" punctuation are not in the GSM-7 alphabet, so one such character switches the whole message to Unicode. Capacity then drops from 160 to 70 characters, or from 153 to 67 per part. The switch applies to the entire message, not just the character that caused it.

Two examples show the effect:

• A 100-character English message fits in 1 part. The same length in Urdu script needs 2 parts.

• A 150-character English message is 1 part. Add one emoji and it becomes Unicode, so it needs 3 parts.

Smart quotes and long dashes pasted from a word processor trigger the same switch without any visible sign. Replace them with plain keyboard punctuation before you send.

Sending SMS in bulk: the basic steps

Sending SMS in bulk takes six steps:

1. Confirm that everyone on the list agreed to receive your texts.

2. Prepare and clean the contact list.

3. Write the template and check its length.

4. Choose a provider.

5. Send a small test batch to your own numbers.

6. Send the full list and review the status report.

Preparing your contact list

Use one row per person with a phone number column and any merge columns, such as first name. Write numbers in international format: a plus sign, the country code, then the number with no spaces, dashes or leading 0. Remove duplicates, and remove anyone who has opted out. Keep a record of when and how each person gave consent. Pakistani numbers have their own format, covered in the Pakistan section below.

Personalising at scale without breaking character limits

A merge field such as {first_name} expands to a different length for every recipient, so the final message length varies. Most senders encode each message separately, so one recipient with an accented or Urdu-script name may receive a Unicode message while the rest get GSM-7. Test the template with your longest name and a non-Latin name. Leave about 20 characters of headroom below a part boundary. Use the tool to personalise your bulk SMS template and see the result per recipient.

Bulk SMS sending in Pakistan: what's different

The mechanics are the same in Pakistan, with the same 160/70 limits, but number format, language and pricing currency differ. A bulk SMS service in Pakistan may be a local operator's business product or an international platform that routes to Pakistani networks. Urdu in Latin letters, often called Roman Urdu, stays in GSM-7 and avoids the Unicode drop. Urdu script is easier to read but costs more parts.

Local number formatting

Pakistani mobile numbers are written locally as 03XX XXXXXXX, eleven digits with a leading 0. International format drops the 0 and adds the country code: +92 3XX XXXXXXX. Spreadsheets often strip the leading 0 from a number column, so store phone numbers as text. Run the list through the tool to validate Pakistani phone numbers before you send.

Currency and cost notes

Pakistani providers may quote in PKR, while international platforms may quote in USD, so convert both to one currency before you compare. Ask for the price per message part rather than per message. Also ask whether Unicode messages are billed per part. This guide lists no Pakistani rates because they vary by provider and change.

Estimating the cost before you send

Estimated cost is recipients × parts per message × price per part, when your provider bills per part. A 1,000-person list and a 2-part message means 2,000 billable parts. The same list with a 1-part message means 1,000. Use the calculator to estimate your bulk SMS cost with your own list size and provider price.

Why message parts affect your bill

Many providers count each part as one message for billing, so a longer text multiplies the price. The boundaries are sharp: 161 GSM-7 characters need 2 parts, while 160 need 1. Trimming one word can halve the cost of a campaign. Confirm the rule on your provider's pricing page before you budget.

Where to get a bulk SMS sending service

You can get bulk SMS sending from your mobile operator, from an SMS API platform, or from an online sending service. Three options to compare:

• Your mobile operator's business SMS service. Ask the operator's business sales team whether it sells bulk messaging, which countries it covers and how it handles sender names.

• SMS API platforms such as Twilio, Vonage, Plivo and Sinch. These platforms let developers send messages through an API.

• WaSMS. WaSMS is run by the same team as this site. It is another option to compare at wasms.net.

We have no affiliate relationship with the operators or platforms named above. Compare them on country coverage, price per message part, Unicode handling, opt-out handling, delivery reports and support.

What is bulk SMS sending?

Bulk SMS sending is delivering the same text, or a personalised version of it, to many phone numbers in one job. A bulk SMS sender takes your list, builds each message, splits long ones into parts and passes them to carriers. FreeSMSGateway explains the length rules so you can predict how many parts each recipient gets.

How many characters can I send in one bulk SMS?

One SMS holds 140 bytes, which is 160 GSM-7 characters or 70 Unicode characters. Longer messages are split into parts that hold 153 GSM-7 or 67 Unicode characters each. FreeSMSGateway's SMS character counter shows which alphabet your text uses and how many parts it needs.

Is there a free way to send bulk SMS?

Free options are limited to trial credit from some providers or the texts included in your own phone plan, which suits only small lists. Sending to a large list normally has a per-message cost, so read each provider's terms before relying on a free offer. FreeSMSGateway's SMS cost estimator helps you work out what your list will need before you send.

How do I send bulk SMS in Pakistan?

Put every number in international format, +92 followed by the 10-digit mobile number without its leading 0, then choose a provider that serves Pakistan, such as your mobile operator's business SMS service or an SMS API platform. Check the numbers first with FreeSMSGateway's Pakistan phone number validator. Ask the provider about any sender name or registration requirements before you send.

Does using Urdu text change my message cost?

Yes, it can. Any Urdu letter switches the whole message to Unicode, which holds 70 characters per single SMS and 67 per part, against 160 and 153 for GSM-7 text. A 100-character Urdu message therefore needs 2 parts, and many providers bill per part. FreeSMSGateway's SMS cost estimator helps you check the effect before you send.

What's the difference between a bulk SMS sender and a regular SMS app?

A regular SMS app sends one conversation at a time from your phone and your own plan. A bulk SMS sender takes a contact list, merges personal details into a template, splits messages into parts and sends the whole batch through a provider's carrier connections, usually from a dashboard or API. FreeSMSGateway's guide covers each of these steps.

Sources: 3GPP TS 23.038 (character alphabets) and 3GPP TS 23.040 (message format and concatenation).

Check your message length and estimate the cost before you send: use the SMS cost estimator.