j
Jose
04/11/2026, 11:47 AM@AI Evy Hi! I need a Spanish +34 phone number for outbound calls
to Spain for my AI voice agent. I can see in your docs
that international numbers are supported. How can I get one?
Also, I'm experiencing high E2E latency (4-5 seconds)
when using SIP trunking with a Spanish provider.
ASR+LLM+TTS total is under 2 seconds but E2E is 5 seconds.
Any suggestions to reduce this?
a
AI Evy
04/11/2026, 11:48 AMThanks for tagging me @Jose. I'll look through relevant sources and get back to you shortly.
AI Evy
04/11/2026, 11:48 AM### Answer
## Getting a Spanish +34 Phone Number
For Spanish phone numbers for outbound calls, you have two main options:
Option 1: Use Your Own Number via SIP Trunking [(1) ]()
You can integrate your own Spanish phone number through elastic SIP trunking with providers like Twilio, Telnyx, or Vonage . This allows you to use your existing +34 number with Retell AI agents .
To set this up:
- Configure elastic SIP trunking with your telephony provider
- Import your Spanish number to Retell in E.164 format
- Provide the termination URI to identify your elastic SIP trunk for outbound calls
Option 2: Purchase Through Retell
Retell supports native international calling to 14 countries [(2) ]() . However, based on community reports, there may be limitations with certain international numbers purchased directly through Retell [(3) ]() .
## Addressing Your Latency Issue
For your SIP trunking latency problem (4-5 seconds E2E when ASR+LLM+TTS is under 2 seconds) , this suggests the additional delay is in the telephony/network layer rather than the AI processing.
Recommended Transport Method:
TCP is recommended over UDP due to reliability factors when using SIP trunking [(4) ]() [(1) ]() . Ensure your SIP configuration uses TCP transport [(1) ]() .
Retell's SIP Server Details:
- SIP server URI:
sip:sip.retellai.comsip:sip.retellai.com;transport=tcp18.98.16.120/30143.223.88.0/21161.115.160.0/19AI Evy
04/11/2026, 11:48 AMIP provider about:
- Network routing optimization
- Codec selection (G722, G711U, G711A are supported) [(4) ]()
- Regional SIP server selection closer to Spain
If the latency persists after optimizing your SIP configuration, you may want to test with a different telephony provider or contact your current provider about the routing delay.
AI Evy
04/11/2026, 11:48 AM
To learn more, see the sources I considered:
[[1] Custom Telephony Overview](https://docs.retellai.com/deploy/custom-telephony)
[[2] Platform Changelogs | Retell AI](https://www.retellai.com/changelog)
[[3] Error in Number Formatting](https://discord.com/channels/1186424376300679209/1344337067051716619)
[[4] Telnyx](https://docs.retellai.com/deploy/telnyx)
AI Evy
04/11/2026, 11:48 AMFeel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.