Intex call missing / phone app not working

Yesterday I had a huge problem with Intex Aqua Fish in Finland. When someone calls me my phone doesn't ring or show any info about incoming call but callers phone works as normal soo peep like I'm not aswering. This caller phone normal behaviour should mean that there was something wrong with phone app. We tested calling from different phones and operators and everytime it was same normal on caller phone but nothing in my Intex. This was fixed after reboot, but seems that Intex isn´t reliable in Finland, you can really miss some calls without knowing anything about those.