Same problem.. Volte is not working in m3 note.. I use jiojoin app to call and send sms with jio 4g..
Looks like I will have to report this as bug.

Please use jiojoin app for time being.. This bug will be fixed soon.

Bro You can use Jio sim ..just install jio join ap for calling.

I want to know one thing...r u using default calling app or jiojoin for calling...bcz I am unable to use default calling app in m3 note...

But when we will click in sim and network option under setting ...we will get a option to enable volte in m3 note.

Yes bro facing same issue and jiojoin app is very power hungry app....so you u got any solution please reply.

I think meizu has cheated us because when i got the phone before around 2 months back i asked. Immediately for volte. Support for jio4g and at that time they told me that they will Soon work on it and will update it with next update. But still any update not received on flyme os!! .. Which seems that they have cheated us and on spec. of volte and still it feels lyk that meizu is not intrested to work on it. jio is working with all other volte feature phone there is no any restrication onit.

i wrote to Meizu China and Honkong about this BUG , But they are not replying to my mail...thats the biggest drawback when you buy Chinese stuff here in India...you get poor or no customer service / very few / limited accessories options / no or few spare parts availability ... they have good customer service in China though...now days 3000 rupees mobile gives voLTE and we are begging for fixing bug where we spent more than 300%... its surely not good on Meizu as they will loose their market share soon here in India ... this attitude is certainly not expected from Meizu , where as small small  companies / brands are offering ultra low cost mobiles with such features and are working flawlessly ,i was not expecting such poor service from Meizu coz i have used their products since 2005 when i was in China... hence the reason for buying m3 note instead of Xiaomi but i was wrong...its a shame for Meizu

VoLTE is not working with my jio sim (m3 note). Please solve this issue..

it is JIO SIM Network Lock.  So the JIO SIM Worked in LYF Mobiles Only. the JIO SIM Network Accessed by IMEI Number.

so wait 1 Month.