A recent update by HTC on Google Play is causing a lot of trouble with HTC One M8 and HTC One M7 users as voice calling has stopped working. As of now there is no clear explanation but what is causing the issue or when a possible fix will be released by HTC. In a recent statement to AndroidAuthority a HTC spokesperson said:
we are well aware of the problem and taking full responsibility they are currently gathering data on who all was affected in order push a permanent solution to customers ASAP.
A small number of users have been reporting this issue since November 2cnd but it hasn’t until now came to most users attention. Several One owners have found a temporary solutions to the problem but it seems to vary per device what works and what doesn’t. On most devices, the following method seems to work best: