Which AT&T products are supported?

AT&T IP Flexible Reach, AT&T Business SIP Trunking, and most AT&T Business voice products. The integration pattern is SBC + SIP entity for Open behind your PBX.

Do I have to change my AT&T contract?

No. The AT&T-side configuration stays exactly as it is.

E911 routing stays on AT&T, fully unchanged.

Yes — for any AT&T SIP trunk, an SBC is the standard mediation layer.

Can the AI escalate to my PBX agents?

Yes. SIP REFER returns the call via the SBC into the PBX with the transcript attached.

What does this cost on top of AT&T?

AT&T keeps invoicing carrier minutes. Open charges per resolved conversation.

How long does setup actually take?

30–60 minutes — mostly PBX/SBC change-control.

SIP Trunk

Open for AT&T Business

Pair Open with AT&T Business SIP via your SBC and the AI picks up — AT&T keeps the carrier role, E911, and your existing numbers.

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Setup time: 30–60 minutes
Auth: SBC pairing (TLS + IP allowlist)
Directions: Inbound · Outbound · Call transfer
Pricing: Included with Open

01 — Overview

Can I add an AI phone agent to my AT&T Business SIP setup?

Yes. AT&T IP Flexible Reach and AT&T Business SIP Trunking terminate on your SBC; Open joins as a SIP destination behind that SBC. Your AT&T contract, numbers, and E911 stay where they are.

AT&T Business remains your Tier-1 carrier. Numbers, E911 records, regulatory compliance, and PSTN reach all stay with AT&T. Open joins as a SIP destination on the trusted side of your SBC — the SBC keeps AT&T-side signaling mediated, and Open lives behind it. The PBX you run (typically Avaya, Mitel, Cisco, 3CX, or a hosted Cloud PBX) decides which calls hand off to AI.

For inbound, the call lands on AT&T, traverses the SBC into your PBX, and at the point you want AI to take over the PBX routes the call to Open's SIP entity (also configured behind the SBC). AT&T owns the carrier leg; the PBX makes the routing decision; Open answers.

For outbound, Open opens a SIP session against the SBC using a service-account credential, and the SBC forwards to AT&T. AT&T-side billing sees regular outbound minutes; Open never marks them up.

What the AI does on the call: it listens, reasons over your knowledge base and connected tools, and acts. When the AI needs a human, it warm-transfers back via SIP REFER through the SBC into your PBX, which routes to a queue or skill with the live transcript attached.

E911 stays on AT&T. The AI does not initiate 911 calls; if a customer asks for emergency help, the AI warm-transfers to a human and passes through emergency intent to your existing E911 path.

What stays the same on AT&T Business

AT&T-supplied numbers
DIDs, toll-frees, and regulatory records stay on AT&T.
AT&T contract and pricing
Your AT&T Business SIP / IP Flexible Reach contract doesn't move.
Existing SBC
Your SBC keeps mediating AT&T-side signaling.
E911 routing
Emergency calls keep using your AT&T-side E911.

What's new with Open

A SIP entity behind the SBC
Open's SIP URI becomes a destination on the trusted side of your SBC.
PBX-side routing change
Your PBX routes opted-in calls to the Open SIP entity.
AI handles the conversation
On opted-in branches, the AI greets, listens, calls your tools, and replies in natural speech.
Pricing model
Open per resolved conversation. AT&T keeps invoicing carrier minutes.

02 — Why this works

The native AT&T Business experience

AT&T contract untouched
Your AT&T Business agreement doesn't change.
E911 stays on AT&T
Emergency routing remains on the carrier side.
Per-PBX-route opt-in
Pick exactly which PBX hunt groups, ACD paths, or queues route to AI.
Warm transfer back to your PBX
AI escalations come back via SIP REFER through the SBC into your PBX with the transcript attached.

03 — Setup guide

Wire up AT&T Business in 30–60 minutes

Two trunks — one inbound, one outbound. Both configurable from Settings → SIP in the Open dashboard.

1
Open Settings → SIP
Open the inbound trunk configuration.
2
Pick a SIP region
Choose Global or US.
3
Copy the SIP credentials
Grab the SIP endpoint, username, and password.
4
Add a SIP entity behind your SBC
On the trusted side of the SBC, configure Open's SIP host as a SIP entity / trunk.
5
Wire your PBX to route opted-in calls
In your PBX, add a hunt group / ACD path that routes to the new SIP entity.
6
Add the matching numbers to Open
Under Phone Number (DID), add the AT&T DIDs.
7
Assign numbers to an AI agent
Channels → Phone → Agents → assign DIDs.
8
Place a test call
Dial an AT&T-supplied number, take the AI branch, and confirm Open answers.

04 — Configuration

Settings → SIP, at a glance

A real inbound trunk for AT&T Business looks something like this. Yours are generated when you open Settings → SIP.

SIP entity · AT&T Business

Sample

Carrier: AT&T IP Flexible Reach / SIP
Open SIP host: sip.us.opencx.comUS region
Transport: TLSrecommended
Auth: TLS + IP allowlist (SBC)
E911 routing: On AT&Tunchanged

05 — Security

Encrypted, audited, refundable

SIP over TLS for signaling, SRTP for media. Every call is logged with full reasoning traces. SOC 2 Type II, GDPR-aligned, HIPAA- and PCI-ready. Backed by the Open $2M Refund Guarantee.

06 — FAQ