No receive phone call on LTE 4G

[Tubuntu]

I have a question regarding an issue. I have an unlock phone from China (ht20 pro ) and have changed to Fido LTE sim card. I am able to use the 4G LTE on my phone. No problem speed ok 

While i am using the 4G , if i try to make a phone call or there is an incoming call.,the call won't be connected until the phone changes back to the E network. (CALL DELAY 15 SECOND) 

My phone supports 2600 MHz for the LTE netowork. I am just wondering if there is a way that i can still receive phone call without problem while i am using 4G on the phone 

Looking forward to your reply 

Thanks

[Cawtau · Accepted solution]

Hello Tubuntu,

  Welcome to the community!

  As far as I am aware, these are the band/frequency specifications of that phone:

2G: GSM 850/900/1800/1900MHz
3G: WCDMA 900/2100MHz
4G: FDD-LTE 800/1800/2100/2600MHz

~taken from here and here (and other websites)

  Judging by those specifications, that phone has all of the compatible bands/frequencies for 2G. Note that Rogers intends to decommission the GSM network by December 31, 2020 (see here). Unfortunately, that phone does not have any compatible '3G' bands or frequencies. With regards to LTE, you are correct in that the phone has one compatible band/frequency, band 7 or 2600MHz. You can verify the compatible bands/frequencies here. While the phone should work on the networks, coverage depends on corresponding bands/frequencies on your surrounding cellular towers. You can get an idea of your local cellular towers here. 

  With the exception of voice-over-LTE (voLTE) or Wifi-calling, voice calls and messages are transmitted via the 2G and '3G' networks. After December 31, 2020, they will be transmitted via the '3G' networks. It is normal for phones (without voLTE or Wifi-calling) to standby with a data connection (ie LTE or 4G, etc), and then switch networks when making or receiving voice calls. Since that phone does not have any compatible '3G' bands or frequencies, voice calls will have to be transmitted via the 2G networks. It is unlikely that phone would be supported for voLTE (or Wifi-calling) by the networks so it would not be possible to stay connected to LTE or 4G while making or receiving calls with that phone.

  Not what you wanted to hear, but hope this helps

Cheers