Check if the target is behind a rate-limiting firewall.
If the target is an Avaya IP handset, disregard this message when evaluating network performance.
This message is usually generated when testing to Avaya IP phones. These phones typically have anti-DDOS ICMP filtering. The rate limiting seen here is also similar to other forms of rate limiting, like the type associated with firewalls.
Possible secondary messages
'Typical of Avaya IP phone'
'Loss during test not indicative of actual network response'