Azure Communication Services has built-in limits and quotas for each communication channel to ensure performance and prevent abuse.
graph TD
Limits[Platform Limits] --> SMS[SMS Limits]
Limits --> Email[Email Limits]
Limits --> Chat[Chat Limits]
Limits --> Calling[Calling Limits]
Limits --> API[API Rate Limits]
SMS Limits
| Limit | Description | Value |
| Message Size | Maximum characters per SMS message. | 160 (GSM-7) or 70 (UCS-2) |
| Throughput | Messages per second for toll-free numbers. | 1-5 (default) |
| Rate Limit | Maximum SMS requests per second. | 100 per resource |
Email Limits
| Limit | Description | Value |
| Attachment Size | Maximum size of an email attachment. | 25 MB |
| Recipients per Message | Maximum number of recipients (To/Cc/Bcc). | 50 (default) |
| Sending Limit | Emails per hour (for Azure Managed Domain). | 100 (default) |
Chat Limits
| Limit | Description | Value |
| Thread Participants | Maximum participants per chat thread. | 250 |
| Message Size | Maximum size of a chat message. | 28 KB |
| Threads per Resource | Maximum chat threads per resource. | 10,000 (default) |
Calling Limits
| Limit | Description | Value |
| Participants per Call | Maximum participants in a VoIP call. | 350 |
| Recording Limits | Maximum duration of a call recording. | 24 hours |
| Concurrent Calls | Maximum simultaneous calls per resource. | 1,000 (default) |
API Rate Limits
| Endpoint | Rate Limit |
/sms | 100 requests per second. |
/email | 50 requests per second. |
/chat | 200 requests per second. |
/identity | 100 requests per second. |
See Also
Sources