Some users, particularly in India, have reported that they are unable to acknowledge or respond to an event when xMatters calls them on a voice phone. Even though the call is connected normally, and the person answers the call, they are not given any chance to respond. Instead, xMatters simply plays the notification and hangs up.
The issue also seems intermittent and unpredictable; it does not happen on every call, and does not always happen to specific users.
The cause of this issue can usually be determined by examining the Event logs. In the instances where the response options are not presented, the report indicates that the call went straight to voicemail, even though the recipient answered the phone. When xMatters thinks that a machine has answered, it delivers the message and then says "Good bye", without presenting any response options (because a machine can't submit a response choice).
This is caused by xMatters picking up background noise, usually when the call is answered in a noisy environment, and incorrectly determining that it has reached a machine or voicemail service. (For more information about how xMatters detects whether a call is answered by a machine or a person, see this knowledge base article.)
Sometimes, this issue can be mitigated or eliminated by adjusting the machine detection settings, but this is not always possible in certain situations or environments. Machine detection is subtle and inexact at the best of times, and if your users often work in loud environments, it may be exceptionally difficult to fine tune your deployment properly.
In the meantime, you can help reduce the chances of this happening by advising any users working in a noisy environment that, when answering a call from xMatters, they should press the 'Mute' button on their phones immediately after saying "Hello". This will help prevent xMatters from inadvertently picking up any background noise and incorrectly thinking that a machine has answered the call.
xMatters internal reference: DTN5029