Using your own SIP trunk with zlicx

Many Indian businesses already have numbers and a carrier contract. Moving those is slow and sometimes impossible, so zlicx lets you point an existing SIP trunk at our voice engine. Your carrier keeps carrying the call and billing you for it.

What you enter

In the console, a trunk lives under Numbers. You choose a carrier (Exotel, Vobiz, Plivo, Twilio, Telnyx, Vonage, or a custom SIP provider) and provide:

• Gateways. The host and port your carrier gives you, up to eight. Each can use UDP, TCP or TLS.
• Inbound source IPs. The addresses your carrier sends calls from, up to 32.
• Your numbers, and the agent that should answer each one.

How an inbound call finds the right agent

When a call arrives, we match the dialled number by its last ten digits to find the trunk and agent. We then compare the source IP with that trunk's allowlist.

An empty allowlist means no inbound calls are accepted. That is deliberate. Anyone on the internet can send a SIP request claiming to be your carrier, and a call answered by mistake spends your money. If your inbound test is silently failing, check this list first and confirm the IPs with your carrier, because they often have several signalling addresses.

Billing

You pay your carrier for the phone side of the call as you do today. We do not charge telephony on trunk calls. AI usage and the platform fee still apply, as shown on the pricing page.

Encryption

A gateway can use TLS for signalling, and you can switch on encrypted audio with SRTP. SRTP requires TLS, because the media keys travel in the signalling messages. Plain UDP is still the default, as many carrier setups expect it.

What has been tested, and what has not

We would rather you hear this from us now than during your pilot:

• Inbound calls over a customer trunk have been verified end to end in our own environment.
• Outbound over a customer trunk has not yet had the same end-to-end run.
• Encrypted audio has been built and tested on the engine side, not yet on a live call with a carrier.
• Exotel, Twilio, Vonage and others are options in the console. Listing a carrier doesn't mean we have run live calls through it, so treat your first calls as a test of that path.

Trunk creation also has to be switched on for your deployment, so ask us to confirm before you plan around it.

A sensible first test

1. Create the trunk and add one number.
2. Add your carrier's source IPs.
3. Attach a short test agent that only greets the caller and ends the call.
4. Call it from a phone on another network, and check the call log.
5. Test audio quality in both directions before you add any business logic.
6. Only then attach your real agent.

If your calls are mostly order updates, the logistics workflow page shows how this fits into a real operation.