Subaccounts in Twilio are accounts that are "owned" by your main account. Using a subaccount, you can segment each of your customers' use of Twilio and keep it separate from all the rest. This will allow you to manage the activity and resources of each customer independently.
⚠️ Important
Your main account credentials will allow you to access resources for any of your subaccounts that fall under the v2010 REST API. However, resources on subdomains, such as studio.twilio.com and taskrouter.twilio.com, must be accessed directly using subaccount credentials (API Keys or subaccount SID + subaccount auth token).
Billing
Twilio bills all subaccount usage directly to your main account. You'll have one Twilio balance for all subaccounts. If your main Twilio account is ever suspended, your subaccounts will also be suspended.
Authenthication
You can use your main account credentials (AccountSid and AuthToken) to access Twilio's REST API for your main account, as well as v2010 API resources for any of your subaccounts. You may also use a subaccount's AccountSid and AuthToken to access the resources of that subaccount. You can not use a subaccount's credentials to access the resources of your main Twilio account or any other subaccounts.
If you're authenticating the helper libraries, pass in your main Account SID and main Auth Token as the first two credentials, and the appropriate Subaccount SID as the third parameter.
When performing CRUD operations within a subaccount, use the subaccount SID and auth token. Alternatively, you can generate API Keys at the subaccount level for authentication.
Main account API Keys are only available to access main account resources. Access to subaccount resources will be denied.
International
We are currently working on ways to help our customers minimize the risk of fraudulent international calls and provide ways for Twilio subaccounts to dial certain international destinations. If you have any questions, please contact support.
Permissions
Subaccounts use the main account's voice and SMS messaging permissions.