I built the conversational flow that sent a custom SMS, which is really helpful so I didn’t have to go to the A2P application process, but the single prompt agent couldn’t customize the SMS message. Why is that, and are there any way around to resolve it?
Hi @krittiya.clark It’s not the agent type, it’s the sending number.
The Send SMS tool and the flow SMS node both give you the same two options. Off Retell’s SMS-approved pool (the no-A2P path) the text is a fixed template you can’t edit. Off your agent’s own number with SMS enabled via A2P, you write the content yourself, static text with variables like {{customer_name}} or a prompt the agent fills in.
So check the sending number in your Send SMS tool config. Switch it to the agent’s number and the content field should appear. If your flow really is sending custom text off a pool number, that contradicts the docs and Retell support should hear about it.
No way around A2P for custom content that I know of. Going out via Twilio direct doesn’t help, same 10DLC rules.
Russell
amplifyautomation.ai
Hello @krittiya.clark This is a deliberate limitation of the SMS-approved Retell number option. When sending from Retell’s pre-approved number pool (to bypass A2P), the message content is a preset template provided by Retell — you cannot customize the text or use a prompt.
The workaround: Switch the sending number to the agent’s associated number. This allows you to write a prompt for the agent to infer the SMS content, use static text, or use dynamic variables. The trade-off is that this path requires your number to have SMS enabled via the A2P application.
This same behavior applies to both the Conversational Flow SMS node and the Single/Multi Prompt Send SMS tool.
Thank You
I can customize the SMS message by selecting “SMS-approved Retell number” for the Conversational Flow, but it didn’t work for the Single Prompt. Why is that?