RingTrunk
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FAQ

Frequently asked questions

Short answers to what developers ask before connecting. Everything technical is spelled out in the documentation.

What is RingTrunk?
RingTrunk gives developers an Indian phone number and a SIP trunk to carry calls on it. You connect the platform you already use, such as LiveKit Cloud, self-hosted LiveKit, a Pipecat agent behind LiveKit, or anything else that speaks SIP, and calls flow in both directions. There is a console for doing it by hand and a REST API for doing it from code. RingTrunk is operated by Zingaro AI Private Limited, a company registered in India.
How do I get an Indian phone number for my voice agent?
Request access at ringtrunk.com and tell us what you are building. We set up your account and provide the number. In the portal you create a trunk, attach the number to it, and point your platform at pstn.ringtrunk.com with the trunk id and password. The LiveKit Cloud guide shows the exact configuration.
Does RingTrunk work with LiveKit Cloud?
Yes. One RingTrunk trunk becomes a LiveKit outbound trunk pointed at pstn.ringtrunk.com, a LiveKit inbound trunk that trusts our source IP, and a dispatch rule that puts each caller in a room. If you have configured Twilio Elastic SIP Trunking in LiveKit before, the objects are the same and only the address and numbers change. See Connect LiveKit Cloud.
Does Pipecat work with Indian phone numbers?
Yes, through LiveKit. Pipecat joins a LiveKit room with its LiveKit transport, and LiveKit SIP bridges the phone call into that room over your RingTrunk trunk. Inbound calls land in a room your pipeline joins; outbound calls are placed with the LiveKit API. See Give a Pipecat agent an Indian phone number.
Do I need an SDK?
No. RingTrunk is plain SIP: your platform authenticates with digest credentials to place calls, and accepts our INVITE by source IP to receive them. The REST API is there for automation, not as a requirement. Nothing in your stack has to be rewritten.
What is a SIP trunk?
A SIP trunk is a connection between your voice software and the telephone network over the SIP protocol. Instead of physical phone lines, your system authenticates to a SIP server and sends calls to it, and that server delivers calls to you. On RingTrunk one trunk carries both directions: you get a username (the trunk id), a password shown once, and a server address.
Can I both make and receive calls?
Yes, on the same credentials. Outbound calls are authenticated with SIP digest. Inbound calls to your number are delivered to the origination URIs you list on the trunk, tried in priority order, so a second address is failover. See Placing calls and Receiving calls.
Can I call international numbers or landlines?
No. Destinations are Indian mobile numbers only: 10 digits starting 6, 7, 8 or 9. Landlines, short codes and international destinations are rejected with 403 destination_not_supported.
Can I set my own caller ID?
Only to a number attached to your trunk. Presenting any other number, including a customer's number or a number from another provider, is rejected with 403 cli_not_allowed before the call reaches the network. This is an Indian regulatory requirement, enforced on every call. Attach more numbers to a trunk to use them as caller IDs.
Which codecs are supported?
G.711 A-law (PCMA) with 20 ms packets. Nothing else is negotiated, so restrict your trunk or endpoint to A-law. Offering only G.729 or Opus fails with 488 Not Acceptable Here.
How many concurrent calls can I make?
Every number comes with a number of channels, one channel being one concurrent call, and a trunk's limit is the sum across its attached numbers. A call that would exceed it is refused with 486 Busy Here, and calls already in progress are never affected. There is a separate calls-per-second cap, answered with 503.
Does my call audio pass through RingTrunk?
No. On a RingTrunk trunk the media stream flows directly between the carrier and your SIP server. We do not record, transcribe or analyse call audio. The one exception is callback forwarding, where a forwarded call is relayed live to the forwarding phone, in region and without transcoding, and is not stored.
What if a human needs to answer instead of my agent?
Set a forwarding number on the trunk's Numbers tab, or with forward_number in the API. Incoming calls to that number then ring that phone instead of your SIP endpoints. It is per number, only active while configured, and outbound calling from the number is unaffected.
How much does it cost?
Numbers are priced per month, with one channel included, plus a monthly charge for each additional channel. The exact prices are on the buy screen in the portal before you pay, and there is nothing else on the bill.
Is RingTrunk a Twilio alternative for Indian phone numbers?
RingTrunk is built the way Twilio's SIP trunking is built, with trunks, numbers, credentials, an API and the same response conventions, but for Indian numbers specifically. If your LiveKit project already has a Twilio outbound trunk, the RingTrunk one is the same object with the address changed to pstn.ringtrunk.com and your Indian number in numbers.
Does it work for WhatsApp Business calling?
RingTrunk numbers and trunks are used for voice and for WhatsApp Business calling. Write to [email protected] with your setup and we will send you the settings.
How long does setup take?
Three steps: request access, create a trunk, drop the credentials into your stack. A new trunk can take up to 60 seconds before its first registration succeeds. A rotated password is active within 60 seconds, and the old one keeps working until then.
I am not on LiveKit or Pipecat. Can I still use it?
Yes. Anything that can authenticate with SIP digest credentials and accept an INVITE by source IP connects. The published guides cover LiveKit; for another stack write to [email protected] with what you run and we will send the settings.
Why does RingTrunk carry only Indian mobile destinations?
Because it is built for Indian customers, and the rules that make Indian calls fail on general-purpose platforms are enforced for you here: caller ID from your own numbers, domestic mobile destinations, clean 403 reasons instead of silence. Landlines, short codes and international numbers are not carried, and we say so up front rather than letting a call fail on the network.
Why is G.711 A-law the only codec?
It is the codec Indian mobile networks carry, so there is one telephony codec and nothing to tune. Your platform transcodes between the phone leg and your rooms; LiveKit and Pipecat both do this without configuration. Offering only Opus or G.729 fails with 488 Not Acceptable Here.
RingTrunk is new. How do I know it works?
There is live traffic on the network today, the documentation is open, the LiveKit and Pipecat example is public on GitHub, and the trunk is plain SIP you can verify yourself in ten minutes: register, place a call, receive one. Private beta is a choice about how fast we onboard; the network underneath is production.
Why request access instead of signing up?
Access is a form and a reply. We set up the account and provide the number; you create the trunk with one click and connect. It keeps the numbers we hand out tied to real use, and it means someone has read what you are building before you start.
I build a CRM, dialer or calling product. Can my customers' numbers run on RingTrunk?
Yes. An account can hold many trunks, each with its own numbers, credentials and origination URIs, so one product can give each customer their own number without mixing traffic. Provisioning is a few API calls: create a trunk, attach a number, set where its calls go. See the REST API and Indian virtual phone number API.
We build voice agents on LiveKit and Pipecat. What does the setup look like?
One RingTrunk trunk, one Indian number attached, then three objects in LiveKit: an outbound trunk pointed at pstn.ringtrunk.com, an inbound trunk that trusts our source IP, and a dispatch rule. Pipecat joins the room the call lands in. Guides: LiveKit Cloud, Pipecat, and a runnable example on GitHub.
Where is RingTrunk hosted?
Our network is in Mumbai, India. Inbound calls are delivered from a fixed source IP shown in the portal, and outbound calls are accepted at pstn.ringtrunk.com. Media flows directly between the carrier and your servers.

Still have a question?

Write to [email protected] with what you are building and what you run. Or request access and we will set up your account.

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