Hey Retell team and community! 
I’ve been building voice agents on Retell and absolutely love the platform — but there are a few features that would make it significantly more powerful, especially for international use cases. I’d love to see these added:
1. 
SMS via Any VoIP Provider (Not Just Twilio)
Right now, SMS functionality is locked to Twilio. While Twilio is great, many developers and businesses already have relationships with other VoIP/SMS providers (Vonage, Bandwidth, Plivo, Telnyx, etc.) and may have better pricing or regional coverage through them.
Request: Allow SMS sending through any VoIP provider, similar to how custom SIP trunking works for calls. Even a webhook-based “bring your own SMS provider” option would be a great start.
2. 
WhatsApp Integration (Native Agent Functions)
This one is huge — especially for Asian, European, Latin American, and African markets, where WhatsApp is the primary communication channel, not SMS or traditional calls.
Request: Add a dedicated WhatsApp integration with predefined agent functions such as:
- Send a WhatsApp message
- Read/receive WhatsApp messages
- Send media (images, documents) via WhatsApp
- Trigger WhatsApp flows during or after a call
This would unlock Retell for a massive global audience where WhatsApp is THE default messaging app. This alone could be a game-changer for international deployments.
3. 
More Phone Number Providers
Currently the phone number options are limited. Expanding this would help businesses use their preferred carriers and reduce friction in onboarding.
Request:
- Add more native phone number provider integrations (Telnyx, Vonage, Bandwidth, etc.)
- Custom SIP trunking support (if not already fully available) so we can bring our own carrier
- Third-party provider marketplace/plugin support for flexibility
4. 
Cal.com — Reschedule & Cancel Booking Functions
The existing Cal.com integration is a great start, but it’s incomplete for real-world use cases. Right now we only have:
Check available slots- Book a slot
What’s missing:
Reschedule a booking — The agent should be able to ask for a phone number or unique booking identifier and reschedule an existing appointment- Cancel a booking — Agents should be able to cancel an existing booking on behalf of the caller
Without reschedule and cancel, agents can’t handle the full booking lifecycle. Callers who want to change or cancel appointments have to be redirected elsewhere, which breaks the agent experience entirely. These two functions are critical for any real deployment using Cal.com.
Summary
| Feature | Priority | Impact |
|---|---|---|
| SMS via any VoIP provider | High | Flexibility for existing infra |
| WhatsApp integration | Very High | Global market unlock |
| More phone number providers | Medium | Reduces onboarding friction |
| Cal.com Reschedule + Cancel | Very High | Completes booking lifecycle |
I believe these additions would make Retell significantly more competitive globally and more complete as an end-to-end voice agent platform. Would love to hear if any of these are on the roadmap!
Upvote if you agree! 