If these callers are known numbers then we can work with the number owners to try and replicate the issue and our provider can help with this. If this is the case, please provide details of the problem voicemails to Talkdesk Support.
However, generally, these voicemails or calls are from malicious 3rd parties who are not recognized and will be calling to your Talkdesk toll-free number/s.
For background, when a person makes a call to a toll-free number, there is a “toll” paid by the toll-free phone number owner to the provider initiating the call. It is possible for a malicious party to set up a system where they receive a portion of the toll from the initiating provider when they initiate calls to toll-free phone numbers.
In this scenario, the malicious party is incentivized to make large amounts of automated calls to toll-free numbers. They often do this using modems which play modem or fax like audio tones. This is a form of fraud and is an industry-wide issue for toll-free phone number providers.
Our provider works closely with both regulatory bodies as well as partner carriers to track down the source of these calls.
We also work with the industry to minimize fraudulent use of numbers and have implemented additional monitoring of our available inventory to further ensure that numbers are not receiving unwanted calls before you purchase them.
If you haven't already done so, adding these numbers to your blocklist is the best way to ensure these fraudulent calls do not reach your Talkdesk account.