Onboard your AI Agent to handle Voice conversations over the phone by following the steps in this guide.
Voice onboarding has the following constraints:
A Voice AI Agent allows you to engage with end users over the phone.
Your Voice AI Agent includes the following capabilities:
Get your Voice AI Agent up and running in a few steps. For detailed instructions, see Implementation & usage.
Work with your Ada team to provision Twilio resources (phone number, SIP domain, or Twilio Application). Most customers use Ada-managed Twilio.
On the Ada dashboard, go to Config > CHANNELS > Voice and configure your Twilio settings if using bring-your-own Twilio.
Enable Languages for Voice and choose regional dialects on the Dialects tab.
Configure your Voice AI Agent by completing the following steps in order.
Ada’s Voice AI Agent is powered by Twilio. In almost every deployment, Ada provisions and manages the necessary Twilio resources for you—no separate Twilio contract or configuration required.
Most Voice customers use Ada’s central Twilio account.
If you must use your own Twilio project—for regional compliance or existing contracts—expand the steps below to prepare your:
Purchase a phone number through Twilio. For more information, see How to Search for and Buy a Twilio Phone Number from Console at Twilio’s Help Center.
Port an existing phone number from another service provider to Twilio. For more information, see Porting a Phone Number to Twilio at Twilio’s Help Center.
If you are using a toll-free number with your AI Agent and you want to be able to send SMS messages from it during a phone conversation, you will need to submit a Toll-Free Message Verification request to Twilio. For more information, see Toll-Free Message Verification for US/Canada at Twilio’s Help Center.
If you are using a local number with your AI Agent and you want to be able to send SMS messages from it during a phone conversation, you will need to submit an A2P (Application to Person) 10DLC (10 digit long code) registration request to Twilio. For more information, see Programmable Messaging and A2P 10DLC at Twilio’s Help Center.
Your AI Agent can also receive calls from your contact center infrastructure, transferred over the public internet using Session Initiation Protocol (SIP). To do this, you first need to create a SIP domain in Twilio.
An Access Control List (ACL) is a security measure that manages who can access your network resources by specifying allowed IP addresses. In SIP communications, using an ACL enhances security by ensuring only trusted traffic can reach your Twilio SIP domain, preventing unauthorized access.
This procedure takes you through configuring an IP ACL in Twilio, so Twilio only accepts SIP traffic that originates from your specified IPs. You can also choose to configure credential lists instead, so it only accepts traffic from specific usernames and passwords. For more information, see Inbound - Sending SIP to Twilio at Twilio’s Help Center.
My Contact Center Platform IP Address).After getting your phone number and/or SIP domain set up with Twilio, you can connect it with your AI Agent.
In your Twilio account, you need to obtain your account string identifier (SID), and create an API key to use with Ada.
For information on how to create an API key, see API Keys and How to Change Them at Twilio’s Help Center. When you create an API key, you get both a key and a secret. You can only view the secret once for security reasons, so make sure you save it in a safe place.
For more information on how you can configure your AI Agent with your contact center platform, see Integrate your voice AI Agent with your Contact Center as a Service (CCaaS) provider.
your-domain-name.sip.twilio.com and should be the global unique SIP domain that you previously created. If you haven’t created a SIP domain yet, entering and saving a SIP domain here will create the domain in your Twilio account. You will then need to configure at least one IP Access Control List or Credential List in Twilio to use with this SIP domain.
You can configure additional settings to fine-tune your AI Agent’s behavior during phone calls. Additional settings are covered in later topics.
Your usage of Voice is subject to both applicable privacy and phone communication laws, and Twilio’s policies. These may vary based on your location and industry. If you have any questions, please contact Ada.
Your AI Agent can be enabled to speak multiple different Languages over the phone. For more information on enabling languages, see About multilingual support.
The following languages are available for voice:
If you enable any of the above languages in your AI Agent, that language will be available in both Messaging and Voice - you can’t have any of these languages only enabled for one or the other.
Some of the languages available in Voice also have support for different regional dialects of those languages:
The dialect you choose narrows down which speaking voices will be available for that language. When you choose a dialect for your AI Agent, your AI Agent will automatically use the default speaking voice for that language and dialect. You can always go into your settings and choose a different voice for that dialect instead.
To change the dialects available for your AI Agent:
On the Ada dashboard, go to Config > CHANNELS > Voice, then go to the Dialects tab.
For each language that has dialects available, in the Dialect/region list, select an available dialect.
Click Save. Your AI Agent immediately starts using the dialects you chose for all conversations in the corresponding languages, for both internal testing and for any live voice content in your AI Agent.
By default, your AI Agent determines the language to use with your end user based on the language metavariable. There are a few ways you can set the value of this metavariable:
Set a default language for the phone number or SIP domain
For each phone number or SIP domain that your AI Agent uses to receive phone calls, you will need to assign a default language. When a call is received using that phone number or SIP domain, the end user’s language metavariable will automatically be set to that language.
Let end users select from a menu of enabled languages
You can choose to begin all of your AI Agent’s calls with a menu that allows end users to select one of your enabled languages. If you turn on this menu, your AI Agent will serve it to all end users before the Greeting, even if the number is associated with a specific language.
Toggle the language On or Off to control whether it appears in the menu.
For languages you want to appear in the menu, drag them higher or lower in the list. Your AI Agent will automatically assign each language a number that the end user can dial into their dialpad to select.
Use the End Users API
You can use the End Users API to update a user’s profile to set the language metavariable.
Send language information in the SIP header
If you’re using a SIP domain for your AI Agent to receive phone calls, you can set the conversation language by including a language value in one of the following SIP headers. This overrides the default language configured for that SIP domain.
The language value must be a BCP-47 language code that matches a dialect enabled on your Voice configuration page (for example, es-ES or fr-CA).
There are two supported methods, listed in priority order:
language key-value pair in the SIP User-to-User header. For example: User-to-User: language=es-ES.X-language header. For example: X-language: es-ES.If both headers are present, the UUI header value takes precedence.
Send language information as a Twilio Parameter
If you’re using a Twilio Application for your AI Agent to receive phone calls, you can include the language value as a parameter when transferring a call to the Application.
Choosing a speaking voice for your AI Agent is an important part of your AI Agent’s branding. You can change your AI Agent’s voice at any time to better fit your AI Agent’s branding needs.
To choose a speaking voice:
On the Ada dashboard, go to Config > CHANNELS > Voice, then go to the Speaking voice tab.
Under Speaking voice, select a voice for each language you have enabled in your AI Agent.
Optionally, in the text field, you can type in a text sample, like a message from your AI Agent, so you can hear your AI Agent read out a specific piece of your AI Agent content. Then, you can click the Play button beside a selected voice to play the sample.
Click Save. Your AI Agent immediately starts using the voices you selected for both internal testing and for any live voice content in your AI Agent.
You can choose how much time your AI Agent will wait for an end user to speak before it reprompts the end user.
To configure maximum caller silence:
On the Ada dashboard, go to Config > CHANNELS > Voice, then go to the Configuration tab.
Under Maximum caller silence (seconds), enter the number of seconds you want your AI Agent to wait before re-prompting the end user. After re-prompting the end user, the AI Agent will wait an additional 10 seconds before then ending the call.
Click Save.
Your Voice AI Agent can filter out background noise — such as traffic, crowds, office chatter, and other ambient sounds — before it reaches speech detection and transcription. This prevents background sounds from being mistranscribed as end user speech, which can interrupt conversational flow and reduce your AI Agent’s ability to accurately understand end users.
Background noise cancellation is enabled by default for all Voice AI Agents.
To enable or disable background noise cancellation:
On the Ada dashboard, go to Config > CHANNELS > Voice, then go to the Configuration tab.
Under Background noise cancellation, toggle the setting on or off.
Click Save.
During voice calls, there are moments when your AI Agent needs extra time to process a request — for example, when retrieving information from external systems. Without any audio feedback, callers may assume the call has dropped or the AI Agent has stalled, leading them to speak again or hang up.
Interstitial audio plays a subtle audio cue during these processing moments, signaling to the caller that the AI Agent is still actively working. This reduces caller barge-in events, improves call quality, and creates a smoother overall experience.
You can select from four purpose-built sounds, each designed and optimized for phone audio clarity:
You can preview each sound in the dashboard before saving your selection.
The delay threshold controls how long the AI Agent waits before interstitial audio begins playing. The timer starts after the caller stops speaking or after the AI Agent’s acknowledgement message is spoken — whichever happens last. You can choose a delay between 2.0 and 4.0 seconds.
A shorter delay provides audio feedback sooner, while a longer delay avoids playing audio for requests that the AI Agent can resolve quickly.
To configure interstitial audio:
On the Ada dashboard, go to Config > CHANNELS > Voice, then go to the Interstitial Audio tab.
Toggle Interstitial Audio on to enable the feature.
Under Delay threshold, select how long the AI Agent should wait before playing the sound. The default is 3.0 seconds.
Under Sound, select one of the four available sounds. Click the Play button on any sound card to preview it.
Click Save.
If your business uses brand-specific product names, internal acronyms, or industry jargon that typical speech models might mishear, you can “teach” your Voice AI Agent to recognize them more reliably. By adding a short list of priority terms, the underlying speech-to-text engine will give extra weight to those words and phrases whenever it transcribes a call.
This feature is currently only supported in English. If you have additional languages enabled in your AI Agent, adding terms to your vocabulary won’t affect how your AI Agent interprets those terms in those languages.
You usually need no more than 20–30 high-value terms to see a noticeable boost. Adding more than 50 terms is not recommended. If you have too many terms, there is a risk that some of these may not be included.
To manage your AI Agent vocabulary:
On the Ada dashboard, go to Config > CHANNELS > Voice, then go to the Vocabulary tab.
Add, remove, or dig deeper into the terms in your list as required:
To add a new term, click New Term. A new row in your vocabulary table appears. Type in a term, then click Add term.
To delete an existing term, hover over its row and click the Delete button that appears.
To view all the conversations where end users used a term, beside that term, click View conversations.
By curating this vocabulary, you give the Voice AI Agent the context it needs to understand your end users accurately—leading to smoother conversations and better outcomes for everyone.
Explore additional Voice capabilities and related configuration options.