For both use cases, you can keep it one-way—no two-way SMS is needed. Retell supports sending an SMS during the call, including booking links and follow-up details. However, if you’re using your own number for custom SMS, A2P registration is generally required; Retell’s SMS-approved number pool can avoid that, though it has limitations on message customization. I can help you set up the workflow and find the cleanest approach for your exact use case.