Hi,I'm setting up call forwarding for one of my cl...
# ❓・ai-evy-supportb
B11TENCOURT
04/03/2026, 12:44 PM@AI Evy Hi,
I'm setting up call forwarding for one of my clients and running into an issue.
The clinic recently switched to VOIP phones and was advised to cancel their AT&T landline — but they haven't done so yet. AT&T is currently forwarding their main number to their VOIP system (ADIT).
When the client tried to activate call forwarding to Retell's number by dialing *72 from the office phone, they received the message: "Call cannot be completed as dialed."
This is because the office phones are now VOIP and don't recognize AT&T star codes.
Could you advise on the best way to set up call forwarding to a Retell agent in this scenario? The goal is for Retell to answer calls when staff doesn't pick up (no-answer forwarding).
Thank you!
a
AI Evy
04/03/2026, 12:44 PMThanks for tagging me @B11TENCOURT. I'll look through relevant sources and get back to you shortly.
AI Evy
04/03/2026, 12:45 PM
To learn more, see the sources I considered:
[[1] Forward my mobile number to retell ai via SIP trunkink](https://discord.com/channels/1186424376300679209/1322290041715822685)
[[2] I set up the number via SIP trunking and the agent however when I attempt to make the outbound call.](https://discord.com/channels/1186424376300679209/1346151735265067048)
AI Evy
04/03/2026, 12:45 PMFeel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.
AI Evy
04/03/2026, 12:45 PM### Answer
Hi,
Since your client's office phones are now VoIP (ADIT system) , you'll need to configure call forwarding within the VoIP system itself rather than using AT&T star codes.
Recommended approach:
1. Configure no-answer forwarding in the ADIT VoIP system - Log into the ADIT admin portal and set up call forwarding rules for unanswered calls. You'll forward to either:
- A Retell-purchased phone number, or
- A number you've imported into Retell via SIP trunking
2. If using SIP trunking - You can import the existing number into Retell and configure it to route through your VoIP provider [(1) ]() . This allows Retell to handle calls when forwarded from the VoIP system.
Key troubleshooting points from similar setups:
- Ensure your Retell agent is properly bound to the number [(2) ]()
- Verify the termination SIP URI is correctly configured if using SIP trunking
- If you're using webhooks to initialize variables, make sure they're triggered properly when calls are forwarded (this was a common issue in similar setups) [(1) ]()
Next steps:
Contact ADIT support to configure no-answer call forwarding in their VoIP admin panel. They should be able to set a timeout (e.g., forward after 4-5 rings) and specify the Retell number as the destination.
The AT&T landline forwarding to ADIT, then ADIT forwarding to Retell on no-answer should work once configured properly in the VoIP system.