Did it ever work for you or are you new to 48 and just trying to get started?
If it was working before has anything changed on your phone recently - e.g. settings changes, software update etc.?
What make and model of phone (seems to be HTC M9 but can't be sure)?
Where are you located?
Could you be inadvertently roaming on NI networks thus losing the 48 signal?
Are you near the border?
You haven't clarified if it ever worked ok for you (in the same area)?
You may need to contact 48 support for assistance
Hope this helps.