What sits between the caller and the agent
Every Finn call runs over the public telephone network. Between the person on the phone and the agent's language model there is a chain of components, and each one can fail in a way the agent itself cannot compensate for. This page describes that chain so you know which page to open when something breaks.
The chain, in order:
- A phone number, either provisioned through Finn or brought in over SIP.
- A carrier route, which decides whether the call is delivered, labeled, or blocked.
- Media, meaning the audio stream in both directions plus codec negotiation.
- The agent turn loop, which converts speech to text, runs the model, and speaks the reply.
- A terminal event, which is a hangup, a transfer, or a voicemail drop.
Inbound versus outbound
The agent configuration does not change based on direction. The same Finn can answer your business number and also dial a contact list. What differs is what has to be in place before the call happens.
| Inbound | Outbound | |
|---|---|---|
| Who dials | The caller | The platform, on your schedule |
| Number needed for | Callers to dial | Caller ID on the recipient's phone |
| Assignment | Per-number, via Default Inbound Finn | Per-deployment, chosen at launch |
| Main failure mode | Routing rule sends the call to voicemail | Carrier labels or rejects the call |
| Telephony cost | Usually included in the number's monthly rental | Charged at the destination country per-minute rate |
Both directions cost the same per minute of AI usage. International outbound per-minute rates can be many times a domestic call, so check pricing before you point a campaign at a new country.
See inbound routing and outbound campaigns for the configuration on each side, or start from quickstart inbound and quickstart outbound.
The number layer
You get a number one of three ways: buy it through the dashboard under Settings then Phone numbers, port it in from your existing carrier, or leave it where it is and route calls over a SIP trunk. Buying takes seconds. Porting takes 5 to 15 business days depending on country. Numbers are available in 60 or more countries, and regulated countries such as India, France, and Germany may require business verification before a number is provisioned at all.
All of this is done in the dashboard. There is no endpoint for buying, porting, or releasing a number. The API exposes your existing inventory only, at api-phone-numbers.
Details on capabilities, pools, and release behavior are on phone numbers. SIP trunk setup is on BYOC SIP.
The carrier layer, and why calls get labeled
This is the part most teams underestimate. In the US and Canada, carriers score every inbound call against several signals before deciding how to display it. Two of those signals are yours to control.
STIR/SHAKEN is a cryptographic attestation applied by the originating carrier. Calls placed from a Finn-provisioned number are A-level attested by default and you do not configure anything. If you bring your own number over SIP, attestation depends on your provider, not on Finn. Confirm your provider supports A-level attestation for outbound before you launch.
CNAM registration is the business name shown next to the number. Registration is submitted in the dashboard under Settings then Phone numbers then the number then Caller ID Registration. Carrier review takes 1 to 3 weeks. Until it clears, calls are still attested but the label may read as generic caller information.
Answer rate is itself a carrier signal. Once a number drops below roughly 15 percent answered, carriers begin treating it as a spam source, which reduces answers further. Launching a large volume campaign from a single unregistered number is the reliable way to trigger this. Use a pool instead, sized at roughly one number per 50 concurrent calls, and see concurrency for how the dispatcher spreads load.
India requires DLT registration before calls to Indian numbers connect at all. Without it, carriers block them. Approval typically takes 3 to 5 business days.
Media problems look like agent problems
A call that connects with 5 to 10 seconds of silence is almost always a codec mismatch on a SIP trunk, not a slow model. A call where the agent talks over the caller is a voice and turn-taking setting, covered on agents voice.
How the call ends
Every call ends in a recorded outcome: completed, no answer, busy, carrier rejected, transferred, or voicemail. Voicemail drops are logged but do not incur model cost. Transfers can fail when the destination does not pick up, so configure a fallback. See call outcomes, tools transfer, and call logs.
For symptom-first diagnosis, go to troubleshooting.