Googling the number reveals it's related to Telstra's Talking Text service. Basically if the phone the SMS was sent to is not SMS capable Telstra convert it into a talking text instead where a robot reads it back to you. The problem is I was receiving these calls on my mobile... which handles SMS perfectly well.... so I was stumped as to why Telstra was sending these through to me. The phone calls and annoyance continued for days.
It took me a while but I figured out what the problem was for me and my situation. I have no doubts someone else will have the same issue so I thought I'd make a post.
My desk phone at work is call-forwarded to mobile... So what was happening was a specific person was innocently sending SMSs to me from his mobile but his mobile had my desk phone listed as my primary contact number. Hence I was getting talking text calls on my desk phone... which forwarded to my mobile 4-5 rings afterwards. By the time they connect through to my mobile they're at the end of the default "wait for answer" period and hang up.
How to properly fix it:
- Get the friend/enemy sending SMSs to your desk number to fix it on his end (i.e. change primary contact number to be your mobile rather than desk phone for your contact on his phone).
How to prevent Talking Text from reaching you on mobile:
- Block the 0198339100 number on your mobile. For my Samsung S6 it was a case of clicking [...] next to number and saying "block". It won't stop the friend/enemy from sending SMSs to the wrong spot but will stop your mobile phone from ringing. NOTE: Your desk phone will still ring!
How to disable Talking Text service:
- Disable the message bank service on your desk phone
How to prevent the calls from being forwarded to your mobile:
- Disable call-forwarding on your desk phone.
How to make it work (i.e. keep talking texts from desk phone forwarding to mobile without hanging up):
- Increase the "time to wait for answer" by calling 0198339999 from your desk phone and follow the prompts.
There is a bunch of technical information here if you have other requirements/etc.
Hope this helps someone. Good luck!