Number capabilities

What a capability is

A capability is a per-number flag that decides which traffic that number can carry. It is set by the carrier that issued the number and by the regulations of the country it belongs to. You do not turn capabilities on inside Finn. You choose a number that already has them at purchase time, in Settings → Phone numbers → Buy Number, where the buy flow lets you filter by capability and shows what is available for the country and region you picked.

Not every number supports every capability, and the combination varies by country and by number type. Assume nothing about a number you have not checked. The phone numbers list shows the capabilities of each number in your inventory alongside its country, assigned Finn, and monthly cost.

Number types and what they change

Local numbers are the default and are priced per country. Toll-free numbers typically cost three to five times the local rate and make inbound calls free for the caller. Toll-free is an inbound-oriented product. If you buy toll-free expecting to run an outbound campaign from it, check that outbound voice is actually listed for that number before you build a deployment around it.

Regulated countries, including India, France, and Germany, may require KYC or business verification before a number is provisioned at all. The buy flow prompts you for the required uploads. Until verification clears, the number is not usable, and calls to destinations covered by the missing verification fail at the carrier. See phone-numbers for the purchase path and byo-numbers for porting and SIP.

Capabilities are not the whole story for outbound

A number with outbound voice can still fail to complete calls. Capability answers whether the network will accept traffic from the number. Registration answers whether the receiving carrier will present it well.

In the US and Canada, outbound calls must comply with STIR/SHAKEN attestation, which the platform handles for you, and high-volume numbers should be CNAM-registered so your business name appears on caller ID. An unregistered high-volume number gets labeled "SPAM LIKELY" and answer rates collapse. Registration is submitted in Settings → Phone numbers → [Number] → Caller ID Registration and carriers review it over one to three weeks. See caller-id and spam-labeling.

Destination country matters too. A from-number that is not registered for the country you are dialing will be rejected by the carrier even though outbound voice is listed as a capability on the number.

Capacity is separate from capability

A single number that supports outbound voice cannot carry thousands of simultaneous calls. That is a capacity limit, not a capability limit, and no setting removes it. For parallel deployments, group numbers into a pool and assign the pool instead of a single from-number. A rule of thumb is one number per 50 concurrent calls, with at least ten numbers in a pool. See number-pools and concurrency.

WhatsApp numbers behave differently

WhatsApp Business Calling rides on your WABA phone-number ID, not on a number you rent from Finn. It is inbound-only. You cannot dial WhatsApp users from Finn, voicemail is not supported on that surface, and concurrency is tied to your WABA tier rather than per-number capacity. Recording, transcripts, and analytics match PSTN inbound. See whatsapp-calling.

What to check when something fails

Releasing changes capability permanently

Releasing a number in Settings → Phone numbers → [Number] → Release removes it from your inventory immediately, and released US and Canada numbers enter a 30-day quarantine before reassignment. Released numbers usually cannot be recovered. If a number is critical, port it to a carrier you control rather than releasing it.