Voice Broadcast Deliverability: How to Make Sure Your Calls Reach Their Audience

Email senders have talked about deliverability for twenty years: a message that lands in the junk folder might as well not have been sent. Voice broadcasting has the same problem and far fewer people measure it. A campaign can report 50,000 calls placed while a good share of them never rang a phone, or rang with a warning on the screen.

With Newfies-Dialer you bring your own carrier, which means the whole delivery chain is in your hands. This guide follows a call along that chain and shows what to check at each step.

Newfies-Dialer works worldwide, with customers all over the globe, each using carriers in the countries they call. Some of the details below are specific to North America and are marked as such. The chain itself is the same everywhere.

The five steps between “dialed” and “heard”

Step	What can go wrong	Who controls it
1. The list	Dead numbers, people who never agreed to be called	You
2. The carrier	Broadcast traffic refused, throttled or badly routed	You, by choosing
3. Call signing	A weak or missing STIR/SHAKEN attestation	Your carrier, with you
4. The display	A warning label, or a number nobody recognises	You and the networks
5. The first second	Silence, a clipped greeting, a message cut by voicemail	Your campaign settings

A weakness at any step lowers the number of people who hear the message, and the steps multiply: 90% at each of five steps is 59% overall.

Step 1: start with a list that wants the call

A broadcast to out-of-date numbers produces a low answer-seizure ratio, and carriers watch that figure on every customer. Remove disconnected numbers after each campaign, keep the consent record for every contact, and check the list against your Do Not Call lists and the national registers before each run. In the United States, prerecorded marketing calls generally need prior written consent. Other countries set their own rules, so check them for every destination.

Step 2: choose a carrier that welcomes broadcast traffic

Voice broadcasting produces many short calls, and plenty of carrier contracts forbid exactly that. Tell the carrier in plain words what you will send: volumes, destinations, average call length. A carrier that has agreed to the traffic will route it properly. One that discovers it later may throttle it, block it or bill penalties. Our FAQ on how to choose a carrier covers the commercial side. For deliverability, add these questions:

• Which STIR/SHAKEN attestation level will my calls receive?
• Can I buy my calling numbers from you, or how do I prove ownership of numbers I already have?
• Do you publish a caller name (CNAM) for my numbers?
• What calls-per-second rate do you accept, per trunk and per destination?
• Do you send me the SIP response codes for rejected calls, so I can see blocking?

Step 3: understand STIR/SHAKEN attestation

STIR/SHAKEN is the framework used in the United States and Canada to sign calls. The carrier that puts your call on the network attaches a signature saying how much it knows about the caller. There are three levels:

Level	Name	What the carrier is saying
A	Full	I know this customer and they are entitled to use this calling number
B	Partial	I know this customer, but I cannot confirm their right to this number
C	Gateway	I received this call from elsewhere and cannot vouch for where it came from

You do not sign calls in Newfies-Dialer or in FreeSWITCH. The originating carrier does it, based on what it knows about you. That makes the route to level A a matter of paperwork and number management:

• Use numbers the carrier can verify. The simplest case is calling numbers bought from the same carrier that terminates your calls. If you use numbers from elsewhere, ask what proof of ownership the carrier accepts.
• Complete the carrier’s know-your-customer checks. Company details, use case and contact people. This is what “I know this customer” means in practice.
• Send every call for a number through the carrier that vouches for it. If you fail over to a second carrier that does not know the number, those calls will be signed at a lower level.

Attestation is not a pass. A fully attested call can still be labelled if the number behaves badly. It is the foundation the other steps build on.

Outside North America the mechanisms differ, and many of our customers never deal with STIR/SHAKEN at all because they call Europe, Latin America, Africa, the Middle East or Asia-Pacific. The principle holds everywhere: regulators increasingly require a valid, dialable calling number that belongs to the caller, and networks block calls that do not present one.

Step 4: present a caller ID people can trust

Use real numbers that you own and that ring somewhere when called back. Point them at an inbound message that names your organisation and offers a way to opt out, or at an inbound IVR. People who can find out who called are far less likely to report the number.

Then spread the load. A campaign in Newfies-Dialer can rotate through a list of caller IDs, and caller ID groups can select the number by dialling code or area code, so contacts see a number from their own region. Size the pool to the campaign so that no single number carries the whole volume, and keep the same numbers in service over time. A number with months of normal history is worth more than a new one.

Finally, register the numbers. In the US, the Free Caller Registry passes your company details to the analytics services that advise the mobile networks on how to display calls. It takes a few minutes per batch of numbers and costs nothing.

Step 5: get the first second right

The network has delivered the call and the phone has been answered. Two settings decide what happens next.

Answering machine detection. Answer machine detection chooses between playing the message to a person, leaving it after the beep, or hanging up and retrying. Tuned too cautiously it leaves live people listening to silence. Tuned too loosely it plays the start of your message over a voicemail greeting. Test it on a few hundred calls before a large run and listen to the recordings.

The opening words. Say who is calling in the first sentence, in a recording or with text-to-speech personalised with the contact’s name. Offer the opt-out key early. A listener who knows who is calling and how to stop the calls stays on the line longer, and call length is one of the signals that keeps a number in good standing.

Pace the campaign

A carrier trunk and a destination network can both be overwhelmed. Set the campaign’s call rate to what your carrier agreed, limit retries to a few spaced attempts, and keep calls inside the permitted hours for each contact’s time zone. When a message can go out over three hours instead of twenty minutes, let it. The exception is an emergency alert, where speed matters more than anything else and the carrier should know in advance what a full-speed run looks like.

Read the reports like a deliverability dashboard

After each campaign, look at more than the total:

• Answer-seizure ratio (ASR) by day and by carrier. A sudden drop on a stable list points to blocking or labelling.
• Hang-up causes. A rise in rejected or “busy” results on numbers that used to answer deserves a question to your carrier.
• Call duration. If most answered calls end within the first seconds of the message, look at the caller ID, the opening words and the AMD settings before blaming the list.

The campaign and call detail reports in Newfies-Dialer give you these figures, and they should match your carrier’s own records closely.

A short checklist

1. Clean list, with consent on record and DNC applied.
2. A carrier that has agreed to broadcast traffic in writing.
3. Calling numbers the carrier can verify, for full attestation.
4. A pool of caller IDs that answer when called back, registered with the analytics services.
5. AMD tested and the caller identified in the first sentence.
6. Call rate, retries and calling hours set per campaign.
7. ASR, hang-up causes and call duration reviewed after every run.

This article is general guidance, not legal advice. Rules on automated calls change often, so please check the regulations for each country you call with a legal advisor.

If you want help preparing a voice broadcasting campaign, or are unsure whether voice is the right channel at all (see voice broadcast or SMS broadcast), contact us for a demo and a free trial. We work with customers around the world and can help you set up with a carrier in the country you call.