I was unable to use star codes with obihai 1000 phones for a very long time. It wasn’t really a big deal before but was irritating that I couldn’t find an answer. Thanks to a post from voip.ms wiki i figured out that I had to change the ITSP digitmap line. One just has to add |*xx| after |xx.|
Not sure why this was even the case as it is this issue only relates to Obihai phones. In case anyone is curious I use these phones on a few different systems. They are all Asterisk based. Usually Wazo but sometimes direct to voip.ms.