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Bulk SMS

Exotel's bulk SMS feature allows you to send messages to hundreds or thousands of recipients in a single operation. This guide covers API-based batch sends, CSV uploads via the dashboard, scheduling, and best practices for high-volume messaging.

Bulk SMS Methods​

MethodMax RecipientsUse Case
API -- Same Message100 per requestAlerts, announcements, OTPs to multiple users
API -- Dynamic Messages100 per requestPersonalized messages (name, order ID, etc.)
Dashboard CSV Upload10,000+ per fileMarketing campaigns, promotional blasts
Dashboard Manual Entry100 per sendQuick sends to a small group

Sending Bulk SMS via API​

Same Message to Multiple Recipients​

Use the Bulk SMS API to send the same message to up to 100 recipients in a single request:

curl -X POST "https://<api_key>:<api_token>@api.exotel.com/v2/Accounts/<account_sid>/Sms/bulksend" \
  -H "Content-Type: application/json" \
  -d '{
    "sms": [
      {
        "From": "EXOTL",
        "To": ["+919876543210", "+919876543211", "+919876543212"],
        "Body": "Flash sale! 50% off on all items this weekend. Shop at https://example.com",
        "DltEntityId": "1234567890123",
        "DltTemplateId": "1107160000000012345"
      }
    ]
  }'

Dynamic Messages (Personalized)​

Send unique messages to different recipients in a single API call:

curl -X POST "https://<api_key>:<api_token>@api.exotel.com/v2/Accounts/<account_sid>/Sms/bulksend" \
  -H "Content-Type: application/json" \
  -d '{
    "sms": [
      {
        "From": "EXOTL",
        "To": "+919876543210",
        "Body": "Hi Rahul, your order #ORD001 has been shipped. Track at https://example.com/ORD001",
        "DltEntityId": "1234567890123",
        "DltTemplateId": "1107160000000012345"
      },
      {
        "From": "EXOTL",
        "To": "+919876543211",
        "Body": "Hi Priya, your order #ORD002 has been shipped. Track at https://example.com/ORD002",
        "DltEntityId": "1234567890123",
        "DltTemplateId": "1107160000000012345"
      }
    ]
  }'
warning

Each message in a dynamic bulk send must still match an approved DLT template. Only the {#var#} placeholders should differ between messages. The static text must be identical to the template.

Bulk API Response​

A successful bulk request returns HTTP 202 with individual status for each message:

{
  "request_id": "req_abc123",
  "http_code": 202,
  "response": {
    "sms": [
      {
        "Sid": "sms_001",
        "To": "+919876543210",
        "Status": "queued",
        "StatusCode": 202
      },
      {
        "Sid": "sms_002",
        "To": "+919876543211",
        "Status": "queued",
        "StatusCode": 202
      }
    ]
  }
}

Sending Bulk SMS via Dashboard​

CSV Upload​

For large campaigns, upload a CSV file through the Exotel dashboard:

Step 1: Prepare Your CSV​

Create a CSV file with the following format:

Same message to all recipients:

phone_number
+919876543210
+919876543211
+919876543212
+919876543213

Personalized messages (with variables):

phone_number,var1,var2
+919876543210,Rahul,ORD001
+919876543211,Priya,ORD002
+919876543212,Amit,ORD003

Step 2: Upload and Configure​

  1. Log in to the Exotel Dashboard.
  2. Navigate to App Bazaar > SMS > Bulk SMS.
  3. Click Upload CSV and select your file.
  4. Map columns:
    • Phone Number Column -- Select the column containing phone numbers.
    • Variable Columns -- Map CSV columns to template variables.
  5. Select your Sender ID and DLT Template.
  6. Preview a few sample messages to verify correctness.

Step 3: Send or Schedule​

  • Click Send Now to dispatch immediately.
  • Click Schedule to choose a future date and time.
tip

Always preview your messages before sending a bulk campaign. Check at least 3-5 sample messages to ensure variables are mapped correctly.

CSV File Requirements​

RequirementDetails
File format.csv (comma-separated values)
EncodingUTF-8
Max file size10 MB
Phone number formatE.164 format recommended (e.g., +919876543210)
Header rowRequired (column names)
Max rows10,000 per file (contact support for higher limits)

Scheduling Bulk SMS​

Via Dashboard​

  1. After uploading your CSV and configuring the campaign, click Schedule.
  2. Select the date and time for delivery.
  3. Choose the timezone.
  4. Confirm the schedule.

Via API​

The Exotel API does not natively support scheduling. To schedule SMS via API:

  1. Use a task scheduler (cron job, cloud scheduler, or message queue) on your server.
  2. Trigger the bulk SMS API call at the desired time.
warning

Promotional SMS can only be delivered between 9:00 AM and 9:00 PM IST. If you schedule promotional SMS outside this window, they will be queued and delivered when the window opens.

Rate Limits and Throttling​

LimitValue
API calls200 requests/minute
Messages per bulk request100 max
Dashboard CSV upload10,000 rows per file
ThroughputVaries by plan (contact account manager)

For very high volumes (100,000+ messages), contact your Exotel account manager to discuss throughput optimization and dedicated routing.

Monitoring Bulk Campaigns​

Dashboard Reports​

  1. Navigate to App Bazaar > SMS > Reports.
  2. Filter by date range and campaign.
  3. View aggregate statistics:
    • Total sent
    • Delivered
    • Failed
    • Pending

API-Based Monitoring​

Use the SMS Details API to check individual message statuses by their SID. For bulk campaigns, configure a Status Callback webhook to receive real-time delivery reports.

Best Practices​

  1. Deduplicate your list -- Remove duplicate phone numbers before sending to avoid sending multiple messages to the same recipient.
  2. Validate phone numbers -- Ensure all numbers are in valid E.164 format and are Indian mobile numbers.
  3. Test with a small batch -- Send to 5-10 numbers first to verify template matching and delivery.
  4. Use dynamic messages for personalization -- Personalized messages have higher engagement rates.
  5. Monitor delivery rates -- Track your delivery rate and investigate if it drops below 90%.
  6. Respect DND regulations -- Promotional SMS cannot be sent to DND numbers. Filter your list accordingly.
  7. Stagger large campaigns -- For campaigns over 100,000 messages, stagger sends over multiple batches to ensure consistent throughput.
  8. Include opt-out instructions -- For promotional campaigns, always include unsubscribe instructions in your message template.

Common Issues​

IssueCauseResolution
Partial delivery in bulkSome numbers invalid or on DNDCheck delivery reports for individual failures
CSV upload failsIncorrect format or encodingEnsure UTF-8 encoding and proper CSV formatting
Slow deliveryHigh volume exceeding throughputContact account manager for throughput upgrade
All messages failDLT configuration errorVerify entity ID, template ID, and sender ID

Next Steps​