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I’m trying to set up a voice AI receptionist using...
# ❓・ai-evy-support
a
@AI Evy I’m trying to set up a voice AI receptionist using Retell, but I’m running into a blocking issue with phone connectivity. I have already configured a virtual UK number through Zadarma, and SIP forwarding on their side is active and working. However, in my Retell dashboard I cannot see any “Phone Numbers”, “Telephony”, or SIP configuration options. My agent settings only include: Knowledge Base Speech Settings Realtime Transcription Settings Call Settings Post-Call Data Extraction Security & Fallback Settings Webhook Settings Because of this, I am unable to connect my Zadarma number or complete any inbound call setup. Additionally, I was expecting to see SIP or termination URI configuration options, but these do not appear in my account, and I cannot assign a phone number to my agent. Could you please clarify: Whether SIP / BYO carrier / inbound calling is enabled on my current plan How I can enable phone number connectivity (if available) Whether my workspace supports direct SIP or Twilio integration What the correct method is to connect an external number like Zadarma to receive inbound calls in Retell My goal is to route inbound calls from my existing UK number into a Retell AI agent for call answering and booking automation.
a
Thanks for tagging me @alfieevans. I'll look through relevant sources and get back to you shortly.
### Answer I can help clarify the setup process for connecting your Zadarma number to Retell AI. Based on the available sources, Retell supports integrating custom telephony providers like Zadarma via SIP. There are two primary methods to connect external numbers: [(1) ]() *Method 1: Elastic SIP Trunking (Recommended) * This method allows you to connect your existing telephony provider's infrastructure to Retell using SIP trunking. You'll need to: 1. Set up a SIP trunk with Zadarma and configure your number to point to it 2. Import that number into Retell Method 2: Dial to SIP URI If Zadarma doesn't support elastic SIP trunking, you can dial calls to Retell's SIP URI directly. The Retell SIP server details are: - **SIP server URI**: 
sip:sip.retellai.com
- **IP block for traffic**: 
18.98.16.120/30
(All regions) , 
143.223.88.0/21
(certain US traffic) , 
161.115.160.0/19
(certain US traffic) **Transport methods supported**: - TCP (Recommended) - UDP - TLS For TCP transport, use: 
sip:sip.retellai.com;transport=tcp
Regarding your missing dashboard options: The absence of "Phone Numbers" or telephony configuration sections in your dashboard suggests these features may not be visible or enabled on your current plan. I don't have information about plan-specific feature availability based on the available sources. To proceed with your setup: You'll need to use the [Import Number API]() to import your Zadarma number programmatically, providing: - Your phone number in E.164 format - The Termination SIP URI from Zadarma - SIP authentication credentials if required I'd recommend checking the [Documentation]() for complete API integration steps, or contacting a [certified Re
tell partner]() for hands-on implementation assistance.
​ To learn more, see the sources I considered: [[1] Custom Telephony Overview](https://docs.retellai.com/deploy/custom-telephony) ​
Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.
a
@AI Evy Set up a SIP trunk with Zadarma and configure your number to point to it Import that number into Retell , ive set up the trunking, how do i import it
a
Thanks for the follow-up, @alfieevans. I'll get back to you soon.
Appreciate the feedback! Feel free to ask me again with additional guidance or context.
### Answer To import your Zadarma number into Retell after setting up SIP trunking, you'll need to use the Import Phone Number API endpoint. [(1) ]() API Endpoint: 
POST /import-phone-number
Required Parameters: - `phone_number`: Your Zadarma number in E.164 format (e.g., "+441234567890") - `termination_uri`: The termination URI from your Zadarma SIP trunk (used for outbound calls) Optional Parameters: - `sip_trunk_auth_username`: Username for SIP trunk authentication - `sip_trunk_auth_password`: Password for SIP trunk authentication - `inbound_agent_id`: Agent ID to handle inbound calls - `transport`: Transport protocol ("TCP", "UDP", or "TLS" - TCP is recommended) Example using JavaScript SDK:
Copy code
javascript
import Retell from 'retell-sdk';
const client = new Retell({
 apiKey: process.env['RETELL_API_KEY'], // This is the default and can be omitted
}) ;
const phoneNumberResponse = await client.phoneNumber.import({
 phone_number: '+14157774444',
 termination_uri: 'someuri.pstn.twilio.com',
}) ;
console.log(phoneNumberResponse.inbound_agent_id) ;
For Zadarma specifically, you'll need to replace the 
phone_number
with your UK number and 
termination_uri
with the SIP URI provided by Zadarma for your trunk. If you encounter a 500 error during import, try using tools like Postman to test the API endpoint with your parameters to identify if there's an issue with the request payload. [(2) ]() Once imported successfully, you can assign agents to handle inbound calls on that number. [(1) ]() [(3) ]()
​ To learn more, see the sources I considered: [[1] Import Phone Number](https://docs.retellai.com/api-references/import-phone-number) [[2] when loading number by sip trunk, the api returns 500](https://discord.com/channels/1186424376300679209/1364608404542324817) [[3] AI in SIP Calling & Telephony Solutions | Retell AI](https://www.retellai.com/blog/integrating-ai-with-sip-trunking-and-modern-telephony) ​
Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.
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