# Invoking an API using Insomnia
source: https://developer.mastercard.com/account-to-account-commerce-for-dsp/tutorial/insomnia-ies/step5/index.md

## Invoking an API {#invoking-an-api}

Make sure the Environment IES_ACCREDITATION_TEST_ENVIRONMENT_Sandbox is chosen before executing the APIs.
We are going to showcase executing an API - TC-1_AR_RSVD_BANK_Alias_Type_Emaill. Participants are required to test all mandatory APIs.

1. Choose the Sandbox configuration for the **Accrediation Pack IES for DSP**.

2. Open the folder named **TC-1_AR_RSVD_BANK_Alias_Type_Emaill**.

3. Click on **Alias Resolution Update** and then click "Send."

4. The response will appear on the right-hand side of the page. Validate if the status is 200 OK.