unable to make or receive calls on galaxy s10+ since almost last 3 months

[galaxy-s10-plus]

Hi All, 

For some weird reason I'm unable to make or receive calls on my phone for the last 3 months now. 

I have been using my Samsung Galaxy S10+ over past 5 years and I have been on smarty network for over 3 years now.

However, for some reason, I am unable to to make any outgoing calls using smarty network /sim. nor I receive any calls. instead when someone calls me the mobile data drops or gets disconnected for few minutes (2-3 minutes) while the other party is trying to call me.

However, when it comes to call via internet, through whatsapp / signal or any other app, there's no issue. I am able to both make calls on my galaxy s10+ and also take incoming calls via WhatsApp.

Can anyone help me to fix this issue. I have been facing this issue for almost 3 months now and it is effecting me as I am not able to get connected when employers are trying to get through to me for potential job opportunities.

[SmartyTrousers]

Your phone is most likely not compatible with Smarty's 4G calling, unfortunately. Up until recently, it will have been dropping down to 3G to make or receive calls, but most of Smarty's 3G has now been switched off, hence calls are no longer working. See this page for more information.

[Decembersangel · Accepted solution]

Hi @galaxy-s10-plus 

Your phone isn't on the list for incompatible handsets for the SMARTY 4G network as advised by @SmartyTrousers 
Do you have VoLTE enabled on the phone?
https://videotron.tmtx.ca/en/topic/samsung_galaxys10plus/using_voice_over_lte_volte.html#step=1

You need to see LTE as the network connection to be able to use 4G on SMARTY.
4G is just the label for the 4th Generation mobile network BUT  VoLTE (Voice over LTE) is the actual type of network used  by all networks.

It appears you have WiFi Calling (as Whatsapp etc can be used) to be able to make calls and yet 'normal' calls can't be connected. This suggests that VoLTE is not enabled on your phone.