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What is Airtel SIP trunking used for in a Bolna voice agent?
An Airtel SIP trunk lets a Bolna voice agent answer calls on your Airtel numbers and call out from them, with Airtel carrying and billing the minutes. Bolna has no native Airtel telephony integration and no Airtel preset, so you connect it as a Custom SIP trunk. Airtel doesn't publish its SIP trunk settings, so your Airtel Business account team configures their side.
How do I set up an Airtel SIP trunk with Bolna?
- Get these from your Airtel Business account team: a SIP trunk with at least one Airtel number, the host and port Bolna dials, the IPs Airtel sends calls from, and a SIP username and password if Airtel uses credentials.
- Ask Airtel to send calls for your numbers to
trunk.bolna.aion port5060over UDP or TCP (not TLS), with codecsPCMUandPCMA, and to accept calls from Bolna's IPs15.252.21.46and13.206.230.198. - In the Bolna dashboard, under Deploy, open SIP Trunks and click Create trunk. Pick Custom and enter a trunk name and channels. If Airtel's port is
5060, enter the host in Gateway we dial. Otherwise leave it empty. - On the Carrier IPs step, add each IP Airtel sends calls from. Enter the SIP username and password under Carrier credentials (optional) if Airtel issued them.
- Add your Airtel numbers in E.164 format, such as
+91XXXXXXXXXX, and click Create trunk. If you left the gateway empty, add Airtel's host and port on the Connection tab with priority1. - Pick an agent for each number on the trunk's Numbers tab for inbound calls. For outbound calls, set the agent's Telephony Provider to SIP Trunk and pick your Airtel number as the caller ID.
The full walkthrough is in the Airtel SIP trunk setup guide in the Bolna docs.
Which values does Airtel need from Bolna?
| Setting | Value |
|---|---|
| Inbound address | sip:trunk.bolna.ai:5060, or 15.252.21.46 port 5060 if only an IP is accepted |
| Transport | UDP or TCP on port 5060. TLS is not supported |
| Bolna IPs to allowlist | 15.252.21.46 and 13.206.230.198 |
| Audio (RTP) | UDP 30000 to 40000, to and from 15.252.21.46 |
| Codecs | PCMU and PCMA only |
| DTMF | RFC 2833 |
| Call setup | The INVITE must carry an SDP offer. Delayed offer is refused |
What can you build with Airtel SIP and Bolna?
Contact center lines on Airtel numbers. Map each Airtel number to a Bolna agent for support or sales calls, or set a default agent that answers every number without its own.
Outbound campaigns on your trunk. Run single calls or batches from your Airtel numbers. A trunk allows 1 to 1,000 simultaneous calls, and extra calls wait in the queue for a free channel.
Gateway failover. If Airtel gives you more than one gateway, add up to 8 on the trunk. Bolna tries them in priority order and moves to the next one on a timeout, 408, 478 or 5xx.
Caller lookup on inbound calls. Use from_number or a mapped SIP header to pull the caller's details from your CSV, API or Google Sheet into the conversation.
For other carriers, see the generic SIP trunk page.