### Answer When an MMS message is sent during an active phone call, Retell AI agents can receive and understand SMS messages [(1) ]() . The voice agent processes these messages as part of the ongoing voice conversation context . Based on the available documentation, when MMS is sent during a call, the voice agent handles it as supplementary information to the active conversation . The documentation states that "Agents can receive and understand SMS messages during an active phone call — even if the agent has not sent any SMS" , and that "Whatever is delivered to Retell as part of the message is incorporated into the ongoing voice conversation so the agent can respond with that context" . For standalone SMS conversations (not during calls) , you would configure separate inbound SMS agents on the phone number [(2) ]() . However, the documentation doesn't explicitly detail the routing logic when both a voice call is active AND an SMS chat agent is configured on the same number simultaneously. The key distinction is: - **During an active call**: MMS/SMS goes to the voice agent as contextual input [(1) ]() - **No active call**: Inbound SMS would route to the configured inbound SMS chat agent [(1) ]() [(2) ]() For clarification on the exact routing behavior when both agents are configured and a call is active, I recommend checking the [Retell AI documentation]() or reaching out to their support team.

​ To learn more, see the sources I considered: [[1] Send & receive SMS](https://docs.retellai.com/deploy/enable-sms) [[2] Update Phone Number](https://docs.retellai.com/api-references/update-phone-number) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

Thanks for the follow-up, @jred. I'll get back to you soon.

### Answer Inbound SMS agents handle incoming SMS messages sent to your phone number [(1) ]() . When someone texts your number, the inbound SMS agent receives the message and can respond back to the user . You attach an inbound SMS agent to a phone number to enable two-way SMS conversations . Outbound SMS agents are used when you initiate SMS conversations by sending the first message . You can trigger outbound SMS either through the dashboard by clicking "Make an outbound SMS" button or programmatically using the Create Outbound SMS API [(1) ]() [(2) ]() . Both agent types need to be configured on your phone number for full two-way SMS functionality [(3) ]() . You set up both inbound and outbound SMS agent configurations on the same number to handle both receiving and sending messages .

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

@AI Evy When I send something back to an Outbound SMS message does the inbound respond or the outbound respond? Does it entirely depend on interaction windows?

​ To learn more, see the sources I considered: [[1] Send & receive SMS](https://docs.retellai.com/deploy/enable-sms) ​

### Answer When you reply to an outbound SMS message, the inbound SMS agent handles the response [(1) ]() . Once you set up two-way SMS conversation by attaching chat agents to the number, "the inbound will already work" . The documentation states that you can set up a two-way SMS conversation by attaching chat agents to the number, and "Once the chat agent is attached, the inbound will already work" . The available documentation doesn't explicitly detail interaction windows or session continuity between outbound and inbound SMS agents. Based on the information provided, it appears that inbound SMS agents are configured to handle incoming messages to your number , which would include replies to outbound messages you've sent. For specific details about interaction windows and how session continuity works between outbound and inbound SMS agents, I don't have that information in the available sources.

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

### Answer Based on the available documentation, I don't have specific information about detecting whether a chat is coming through SMS versus online chat channels within Retell AI. The documentation shows that Retell AI supports multiple chat channels including SMS (through phone numbers) [(1) ]() and web-based chat (through the website widget) [(2) ]() , but doesn't explicitly detail methods for programmatically detecting or differentiating the channel type during an active conversation. For SMS conversations, you would configure inbound and outbound SMS agents on your phone number [(1) ]() . For web-based chat, you would use the chat widget implementation [(2) ]() or the Create Chat Completion API [(3) ]() . However, the available sources don't specify webhook parameters, API response fields, or other mechanisms that would indicate the originating channel. To implement channel detection for your use case, I recommend: 1. Check out these potentially useful sources: [Get Phone Number]() , [Create Chat Completion]() , [Retell Website Widget]() 2. Contact Retell AI support for clarification on channel detection capabilities Would you like me to try to answer this generally based on my knowledge instead?

​ To learn more, see the sources I considered: [[1] Get Phone Number](https://docs.retellai.com/api-references/get-phone-number) [[2] Retell Website Widget](https://docs.retellai.com/deploy/chat-widget) [[3] Create Chat Completion](https://docs.retellai.com/deploy/create-chat-completion) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.