In some languages text to speech can interpret large numbers in an unintuitive way. Ticket number 1234 may be pronounced "Ticket number twelve hundred and thirty-four" or "Ticket number one two three four". To make sure a larger number is pronounced correctly you can use Speech markdown (SSML). See the voices overview in the developer documentation to make sure your chosen voice supports SSML.
In the flow you can add speech markdown in brackets to a number to make sure the bot interprets it correctly: [number] or [digits] respectively.
