fetch-incoming-phone-number-assigned-add-on-extension

fetch-incoming-phone-number-assigned-add-on-extension: func(params: fetch-incoming-phone-number-assigned-add-on-extension-params) -> result​<api-v2010-account-incoming-phone-number-incoming-phone-number-assigned-add-on-incoming-phone-number-assigned-add-on-extension, string>;