post https://app.bitgo.com/api/v2/user/accesstoken
Create an access token to use BitGo APIs. BitGo restricts access tokens in the production environment to specific IP addresses. However, access tokens in the test environment don't require an IP address restriction. If you omit a spending limit, you must unlock the token using the Unlock session endpoint on a regular basis to permit operations such as withdrawals. Therefore, BitGo recommends including a spending limit.