Issue
When attempting to use an Indian phone number (+91) as a participant in a Group Texting setup within Twilio Conversations Classic, messages are not being received by the intended recipients.
Product
Twilio Conversations Classic
Environment
legacy Twilio Console
Cause
This issue stems from how international SMS is handled by Indian telecom carriers. When Twilio sends messages to mobile numbers in India:
- The sender ID (MessagingBinding.Address) is automatically replaced by the receiving carrier with a random short numeric ID (typically 5 to 9 digits).
- This behavior is standard for A2P (Application-to-Person) messaging in India and is beyond Twilio’s control.
- As a result, replies from participants may not route properly, breaking the group messaging experience.
Resolution
Twilio only supports Group Texting using +1 (US & Canada) long code phone numbers. Toll-free numbers and short codes cannot exchange group texts from Twilio. Therefore:
- Do not use Indian (+91) numbers as the MessagingBinding.Address when adding participants to a group conversation.
- Toll-free numbers, short codes, and non-US/Canada long codes (including Indian numbers) are not compatible with group SMS messaging in Twilio Conversations Classic.
- For successful delivery and functionality of group text messaging, ensure all participants use US or Canadian long code numbers.