The SIP trunk built for Retell AI agents

Yes. didlogic connects to Retell through elastic SIP trunking, which is Retell’s recommended path for production numbers. You set the didlogic regional proxy as your Termination URI, authenticate with your 5-digit SIP login and password, and forward your didlogic number to your Retell SIP address. A test call typically goes through within minutes of finishing setup. A step-by-step guide is published on the didlogic docs.

Buy a DID in the didlogic portal, then in Retell open Phone Numbers and choose “Connect to your number via SIP trunking.” Enter the number in E.164 format, set the Termination URI to your nearest didlogic proxy, and add your SIP login and password. Back in the didlogic portal, forward the number to [email protected]. Assign an inbound or outbound agent and place a test call.

Two differences. First, no per-channel fees, which is the line item that grows fastest on outbound AI campaigns. Second, deeper global DID coverage, 130+ countries with licensed local voice in 17, versus a smaller direct-coverage footprint. Retell connects to both through the same elastic SIP trunking path, so what changes is the telephony layer underneath. See our Twilio alternative for AI voice page for a full breakdown.

Retell bills its own per-minute rate for the AI agent. didlogic is a separate telephony layer billed per DID and per minute, with no per-channel charges. You pay Retell for the agent and didlogic for the numbers and minutes underneath. The two are independent line items.

Yes. The same SIP account handles single outbound calls, batch campaigns uploaded as CSV, and calls triggered through the Retell API. Because didlogic does not charge per concurrent channel, batch concurrency scales on the carrier side without a telephony tier upgrade.

Yes. Retell’s Call Transfer function can use SIP REFER to hand a caller to a human. SIP REFER needs to be enabled once on your didlogic account, so contact your account manager before you configure it. The transfer destination uses the format sip:number@proxy:5060 with the transfer method set to SIP REFER.

On the didlogic side you forward inbound calls to [email protected] and point your trunk at a didlogic regional proxy such as sip.nl.didlogic.net. Because Retell’s SIP server does not use a static IP, username and password authentication is the recommended method rather than IP allowlisting.

Yes. didlogic supplies numbers in 130+ countries, including markets where most providers have gaps, such as parts of MENA, Southeast Asia, and Africa. Once the number is provisioned on didlogic and connected through elastic SIP trunking, it works with your Retell agents like any other number.

Yes. didlogic supports paperless LNP in 8 countries and manual porting in most others, with no downtime during the move. A common pattern is porting numbers to didlogic for voice while keeping another provider for SMS. Retell does not care which carrier owns the number once it is connected by SIP trunk.

This is usually RTP inactivity. When the agent is processing, no audio flows in either direction, and intermediate devices can time out the media stream. didlogic keeps the media path live across those gaps. If you see drops on another provider, the fix is RTP keepalives or a longer RTP inactivity timeout on the carrier side.

didlogic is the telephony layer underneath either one, so the choice of orchestrator is yours to make on features and pricing. If you run both, the same didlogic numbers and SIP account work across them. See our Vapi SIP trunk page for that setup.

Yes. If you already hold carrier relationships or numbers, didlogic supports a bring your own carrier (BYOC) model alongside our own DID inventory, so you can consolidate routing for your Retell agents on one network.