Skip to main content
Keep your numbers on a Twilio Elastic SIP Trunk and have a Bland agent answer them. Twilio sends inbound calls to Bland over TLS with SRTP, and Bland places outbound calls through your trunk’s termination URI. Your numbers stay on your trunk, and Bland never gets your Twilio API credentials. You can split numbers between Bland and your own PBX.
Want Bland to run calls on your Twilio numbers without any SIP setup? Use Custom Twilio instead. It connects your Twilio account to Bland by API.

​
What works

  • Inbound calls to your agent
  • Outbound calls from your agent
  • Transfers from your agent, with SIP REFER

​
Prerequisites

  • A Twilio account with Elastic SIP Trunking, and the numbers you want to use
  • A Bland account with SIP trunking enabled. If there is no SIP tab under Phone numbers, contact Bland support

​
Configure Twilio

1

Create the trunk

In the Twilio Console, go to Elastic SIP Trunking, then Trunks, and create a trunk. Name it, for example Bland.
2

Turn on Secure Trunking and Call Transfer

Under General, turn on Secure Trunking. Twilio then rejects any unencrypted call, which matches Bland: TLS signaling and SRTP media.On the same page, turn on Call Transfer (SIP REFER), and transfers to the PSTN if your agent transfers to phone numbers. Leave Caller ID for Transfer Target on Transferee so the target sees the original caller.
3

Point origination at Bland

Under Origination, add an origination SIP URI for your Bland region, with TLS on port 5061:
Use sip: with ;transport=tls, not sips:. Use port 5061 exactly: Bland reserves its other SIP ports for its own carrier connections. The other regions are under Connection endpoints.Bland already trusts Twilio’s published signaling IPs, so there is nothing to allow-list.
4

Add your numbers

Under Numbers, associate the numbers your agent should answer with the trunk.
5

Create termination credentials

Skip this if you only need inbound calls.Under Termination, note your termination SIP URI, for example yourcompany.pstn.twilio.com. Under Authentication, create a Credential List with a username and password, and attach it to the trunk.Use a credential list, not an IP access control list. Bland’s outbound calls don’t come from a fixed set of IPs you can list.

​
Configure Bland

1

Open the setup wizard

At All agents, go to Dispatch, then Phone numbers, then the SIP tab, and press Create trunk.
2

Provider

Pick Twilio and enter your termination SIP URI, for example yourcompany.pstn.twilio.com. No port needed. The wizard skips the firewall step for Twilio.
3

Authentication

Pick IP-based, and leave Outbound routing on Via Bland’s carrier. Under Outbound call credentials, enter the username and password from your Twilio credential list. Press Create trunk.
4

Numbers

Add each number in E.164 format, for example +14155550100.
5

Assign an agent

Under Phone numbers, press Configure on the number and pick the agent under Assignment.
You know it worked when a call to the number reaches the agent and shows up on the trunk’s Overview tab. For outbound, use the number as from in POST /v1/calls.

​
Caller ID and transfers

Twilio only accepts outbound calls whose caller ID is a number on your Twilio account or a verified caller ID, in E.164 format. Place outbound calls from a number on the trunk. The same rule shapes transfers. When Bland bridges a transfer, the target can’t see the original caller, because that number isn’t on your account. With SIP REFER, Twilio places the transfer itself and shows the original caller. To transfer with REFER, turn on Hand off via SIP REFER in the agent’s Transfer Call node and enter the target in E.164 format. Bland leaves the call once Twilio takes it. Twilio can’t transfer to emergency numbers, and plays no early media during a REFER. See Transfers for every transfer method.

​
Common failures

Check the origination URI is sip:<region>.sip.bland.ai:5061;transport=tls, and that Secure Trunking is on.
The number isn’t attached in Bland. Attach it on the trunk in E.164 format.
The username and password in Bland don’t match the credential list attached to the trunk.
The caller ID isn’t a number on your Twilio account, or isn’t in E.164 format. Call from a number on the trunk, with the +.
Call Transfer (SIP REFER) is off on the trunk, or transfers to the PSTN aren’t allowed. Turn both on.
Secure Trunking is off. Twilio and Bland both need SRTP with AES_CM_128_HMAC_SHA1_80.

​
Next steps

Transfers

REFER, new INVITE, and warm transfers.

Custom Twilio

Connect your Twilio account by API instead.
Docs for agents: llms.txt