Increasing Your Outbound Call Answer Rates


If you’re using Aculab Cloud for outbound calling, for example to remind people of appointments or notify them of utility supply outages, it is in everyone’s interest for you to get the best possible answer rates. You’ve likely heard of the STIR/SHAKEN mechanism, deployed in the US and Canada, which allows people to judge the authenticity of the Caller IDs on their incoming calls. Also, you’ve likely seen the text, and sometimes graphics, accompanying incoming calls on mobiles, allowing people to see the name of the company or person calling.

This page explains best practice for increasing your call answer rates, including how these mechanisms work, and how you can use them. Where certain pieces of advice are country or region specific, this is noted.

Attest your Caller IDs where possible

In the US and Canada, the STIR/SHAKEN framework provides a mechanism to attest that the Caller ID used to place a call is genuine and one which the person or company placing that call has the right to use. This allows the person receiving the call to judge whether they trust its Caller ID. On Aculab Cloud, a call will be placed with a high level of attestation only if the Caller ID is a number purchased through our service. It is not possible for us to attest Caller IDs to a high level in other circumstances, even if you own them through another provider or carrier. This is in common with all CPaaS providers, and is likely to be the case until STIR/SHAKEN certificate delegation (or similar) is adopted.

The first thing to do is to get the Caller ID right – the remainder of this advice depends on it. In order to give your call recipients the highest level of confidence that the Caller ID is genuine, you need to use Caller IDs purchased from Aculab Cloud (US only). Always use Caller IDs which you have the right to use.

Use each Caller ID for only a single use case

There are various call analytics systems which map Caller IDs to text and graphics, showing which person or company is calling. Some of these use crowd sourcing as one way to classify the purpose of the calls for which each Caller ID is used. In order to give these systems the best chance to classify correctly, use each Caller ID for only a single use case. For example, if you place collection and appointment reminder calls, use a different Caller ID for each.

Place in-country calls

Ensure that the Caller ID has the same country code as the dialled number, for example ‘1’ for the US and Canada, or ‘44’ for the UK. This is for a number of reasons:

  • People are more likely to answer an in-country call.
  • Between-country calls are more likely to be classified as spam, and thus blocked.
  • STIR/SHAKEN does not yet work for between-country calls, thus losing the advantage of Caller ID attestation (US and Canada only).
  • Between-country calls may attract surcharges.

Accept inbound calls

Create a basic Aculab Cloud application to answer incoming calls to your Caller ID, and play a message explaining what it’s used for. On Aculab Cloud, this can be as simple as enabling a maintenance message for the Caller ID number’s Inbound Service.

Treat people well

Create a great in-call experience by designing your IVR dialog to be intuitive and easy to use and, if appropriate, having well-trained and helpful contact centre agents. Further, Aculab Cloud’s 99% accurate AI-driven Answering Machine Detection much reduces the proportion of silent calls (likely to be classified poorly) and lets you deliver the right message much more of the time.

Get your Caller IDs known: CNAM

Caller Name Delivery (CNAM) is a system used in the US telephone networks to provide the caller name. It’s been around for many years, does not provide a complete solution, but remains a useful input to call analytics systems. If you’d like to set the CNAM on any of your Aculab Cloud numbers, contact support and we’ll arrange that for you (US only).

Register your Caller IDs


Register your Caller IDs with any appropriate country-specific bodies.

In the US, one such example is the Free Caller Registry, which registers them free of charge with, at the time of writing, First Orion, Hiya and Transaction Network Services. These are significant players in the call analytics market (see below), used by the major US wireless carriers. For example, and again at the time of writing, AT&T CallProtect uses Hiya (US only).

Call analytics systems

In addition, you can register your Caller IDs direct with call analytics providers, for example:

From the user perspective, these provide mobile phone apps which users can install to classify, and in some cases handle (e.g. hang-up if suspected spam), their incoming calls. From your perspective, as well as registering your Caller IDs, these providers generally expose statistics on the performance of your calls, and notify you if they begin to class them as spam. However, bear in mind that a provider’s statistics can only cover the calls they see, for example those placed to phones with their app installed. While this may be representative of your calling patterns, it will not be the whole picture.

You can also register them with mobile phone OS providers, currently just: