SIP trunk options for AI voice agents in India fall into three groups: licensed telecom operators (Tata Tele Business Services, Airtel, Jio, Vodafone Idea), cloud telephony providers that offer SIP to voice AI platforms (Exotel's Virtual SIP Trunking, Plivo, Vobiz), and the AI platform's own telephony. In India, compliance narrows the choice more than price does: calls to Indian numbers must enter and leave the public phone network through licensed carriers, and domestic VoIP-to-PSTN dial-out over the public internet remains restricted. Pick a provider that handles that for you.
This guide explains the rules in plain language, compares the providers, and lists what an AI voice agent actually needs from a trunk, including latency and redundancy.
Why is SIP trunking in India different?
Three facts shape every decision:
- Domestic VoIP-to-PSTN dial-out is still restricted. Ozonetel's March 2026 regulatory summary says domestic VoIP dial-out to Indian mobiles and landlines "remains banned", that the Telecommunications Act 2023 "does not automatically lift this ban", and that new DoT authorisation rules are still pending (Ozonetel).
- Licensed providers carry the calls. Calls that touch the Indian public network go through licensed operators or authorised virtual network operators. Exotel, for example, describes itself as a Unified License Virtual Network Operator providing "compliant PSTN ingress/egress" for voice AI platforms (Exotel).
- Where the call terminates matters. Vapi's documentation states: "Indian phone numbers cannot be used with Plivo on Vapi due to TRAI regulations. These regulations require SIP termination to occur via an Indian server" (Vapi docs). A platform that terminates calls abroad may not be able to use Indian numbers at all.
This is a practical summary, not legal advice. For large deployments, confirm your architecture with your provider.
SIP trunk providers in India compared
| Provider | Type | How it connects | Published notes (Sept 2026) |
|---|---|---|---|
| Tata Tele Business Services | Licensed operator | Dedicated circuit to your premises or PBX | Enterprise contracts |
| Airtel Business | Licensed operator | Dedicated circuit to your premises or PBX | Enterprise contracts |
| Jio Business | Licensed operator | Dedicated circuit to your premises or PBX | Enterprise contracts |
| Vodafone Idea Business | Licensed operator | Dedicated circuit to your premises or PBX | Enterprise contracts |
| Exotel vSIP | UL VNO cloud telephony | SIP to your SBC, PBX or voice AI platform | Built for voice AI and contact-centre platforms; G.711 codecs; SIP over TCP or TLS; static IP for outbound |
| Plivo SIP trunking | Cloud SIP trunking | SIP trunk with Indian domestic numbers | Inbound and outbound at Rs 0.38/min, 30-second pulse |
| Vobiz | SIP trunking for voice AI | SIP trunk plus voice APIs | Pay per minute, no monthly minimum; claims sub-80 ms average round-trip latency |
How to read it: licensed operators suit enterprises that already run an on-premise PBX and want a direct carrier contract. Cloud providers suit teams running AI agents or a cloud contact centre, because they deliver SIP straight to the platform without new circuits.
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What does an AI voice agent need from a SIP trunk?
Use this as a checklist when you talk to any provider:
| Requirement | Why it matters |
|---|---|
| Inbound and outbound | Answer calls on your numbers and run outbound campaigns on the same trunk |
| Enough concurrent channels | Your peak parallel calls, including outbound campaigns |
| Authentication method | Static IP (IP whitelisting) or SIP registration with username and password |
| Transport | UDP, TCP or TLS; match what the provider supports |
| Codecs | G.711 (PCMU / PCMA) is the common denominator for phone audio |
| Number formatting | Whether numbers are sent as +91 E.164 or without the plus |
| Outbound compliance | DND scrubbing, 140-series for promotional and 1600-series for regulated service calls |
| Call records | CDRs and recordings for reconciliation and audits |
Low latency and redundancy: what to ask
Two questions show up again and again when teams choose a trunk for AI calls: "which providers give low latency in India with easy SIP integration?" and "who offers redundancy with multiple points of presence?" Ask these five things:
- Where are the points of presence, and is media handled in India?
- How far is the trunk from where the AI runs? Every extra network hop adds delay before the agent can reply. Test with real calls, not just a ping.
- Is there automatic failover between PoPs, and can you add a second provider?
- Can the AI platform spread calls across several trunks or numbers? On Edesy, outbound campaigns can distribute calls across multiple numbers and credentials (round-robin, least-used or weighted), so a single trunk is never a single point of failure.
- What happens at peak? Confirm channel limits and how overflow is handled. An Erlang B calculator estimates how many channels your peak hour needs.
Three ways to connect a trunk to an AI voice agent
1. Bring your own trunk (BYOC). Keep your carrier, numbers and rates, and connect the trunk to the AI platform over SIP. On Edesy you add your carrier, choose static-IP or registration authentication, set inbound and outbound gateways with the transport your carrier supports, whitelist Edesy's SIP IP, and point a number at an agent. Our step-by-step guide to connecting your own SIP trunk covers it, and the bring-your-own SIP trunk feature page summarises it.
2. Use a provider-native integration. If you are on Exotel, Plivo, Vobiz or Twilio, you may not need SIP at all: the AI platform connects to the provider's API directly. For Exotel, that means the Voicebot Applet, explained in our Exotel AI calling setup guide. Our comparison of SIP trunks vs provider integrations helps you choose.
3. Get a trunk if you do not have one. If you are starting from scratch, Edesy also offers SIP trunking with Indian numbers that plugs into your PBX or your AI agents.
Once the trunk is live, the next decision is how to run calls on it. Our AI outbound calling guide covers campaigns, retries and cost per call, and TRAI regulations for AI calling covers the calling rules.
FAQ
Is SIP trunking legal in India?
Yes, through licensed providers. Calls to and from Indian phone numbers must enter and leave the public telephone network through DoT-licensed operators or authorised virtual network operators, and domestic VoIP-to-PSTN dial-out over the public internet remains restricted. Buy SIP trunks from a licensed operator or an authorised provider rather than an unlicensed route.
Which SIP trunk provider is best for AI voice agents in India?
It depends on your setup. Enterprises with an on-premise PBX usually buy from licensed operators such as Tata Tele Business Services, Airtel, Jio or Vodafone Idea. Voice AI platforms and cloud contact centres often use cloud providers built for this, such as Exotel's Virtual SIP Trunking, Plivo's SIP trunking with Indian numbers, or Vobiz.
Can I use a US SIP trunk or US voice AI platform with Indian numbers?
Often not directly. Vapi's own documentation says Indian numbers cannot be used with Plivo on Vapi because TRAI regulations require SIP termination via an Indian server, which Vapi does not currently support. Check where a platform terminates calls before you buy Indian numbers for it.
How much does a SIP trunk cost in India?
Rates vary by provider and contract. As an example of a published rate, Plivo lists Indian SIP trunking at Rs 0.38 per minute for inbound and outbound with 30-second pulses as of September 2026. Licensed operators and cloud telephony providers usually quote per contract based on volume, channels and numbers.
What does an AI voice agent need from a SIP trunk?
Inbound and outbound calling, enough concurrent channels for your peak, a supported authentication method (static IP or SIP registration), a matching transport (UDP, TCP or TLS), common codecs such as G.711, correct +91 number formatting, and DND scrubbing plus the right number series for outbound commercial calls.
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