From August 8, 2019, onward for the next 1 964 days, call21st.com was checked for availability 6 times. Out of all the tests carried out, call21st.com was accessible 6 times, the last instance being July 13, 2024, when a code 200 was received. All testing performed of call21st.com as of December 23, 2024, found zero instances of inoperability. As of December 23, 2024, no response had an error, according to all of the responses that were received. For call21st.com, the average response time is 2.539 seconds, but on July 13, 2024, it responded in 3.095 seconds.