Unsent Visual text messages becoming phone calls???

[rexone]

I am totally baffled.
Updated my wifes iPhone 6 to iOS11 & my daughter was playing around sending some text messages to show my wife how some of the cute features like Digital Touch work.
For some reason the messages wouldn't send, got the 'Not Delivered' alert.
About 10-minutes later our home phone (landline) rang from 0198339100 with a recorded 'text to speech' message quoting my wife's mobile phone number with the unsent message converted to a robot speech message.
W... T... F... ???

 

[BrianBaughn]

Your daughter texted your landline from your wife's iPhone and your landline service has a text-to-speech feature that is common. You can log into your landline provider's website for an explanation of the feature and to see what other features are included with your plan.