From TJC

I try flash modem EU on Intex. It's not work and try erase modemst1, modemst2 and flash persist.
Try with QTSP and QXDM flash values from Jolla C on Intex (like manual unlock bands on OnePlus One ).
Try custom values. Driver to connect with QTSP/QXDM in Diagnostic mode https://yadi.sk/d/by5jzvtZuVZwH (Lenovo Diagnostic Interface)

It's all not work.

Thanx Coderus and russian community, who trying with me and help.

Have any ideas ?

change the antenna, since zendesk said jollac has a different one :P
i am joking, thanks for updates

I think about this

i created a monster. ahaha

It is quite possible that the radio in the Intex does not have the European LTE bands in it and no software mods will fix this. This would be a hardware issue of the radio not being capable of working on those frequencies.

it's the same phone from the same factory with different back cover.

Well I think I read somewhere on an official statement, that it's not only the backcover that is different, but also the modem is a different one.

Yeah, itdoesntmatt got that exact reply from jolla zendesk:
I am still puzzled:

1. The baseband processor should support all LTE bands
2. The antenna should be no issue, as the frequency range is almost the same (824 -2400 MHz - Aqua fish vs. 791 - 2690 MHz - Jolla C)

Still, with my (extremely) limited knowledge of HW-design in mobiles there could be 100 of other parts which differ and I didn't think of...

I do not know is this the case with Jolla-C vs Intex but In general Snapdragon processor can be the same but if modem is different then you get different supported frequencies.
https://www.qualcomm.com/products/snapdragon/modems

And for general example modem X5 have multible versions:
https://www.qualcomm.com/products/snapdragon/modems/x5
MDM9628
MDM9625
MDM9320
MDM9225

https://www.qualcomm.com/news/releas...gher-speed-lte
"The new chipsets will support LTE Category 4, offering up to 150 Mbps downlink data rates and 50 Mbps uplink data rates. Other standards supported by the MDM9625 chipset include HSPA+ Release 9, EV-DO Revision B, EV-DO Advanced and TD-SCDMA, while the MDM9225 chipset supports HSPA+ Release 9 and TD-SCDMA."

Edit:
Someone mentioned different frequency ranges so it would mean that compination of Modem or Modem+RF-unit would be different.
https://www.qualcomm.com/news/releas...f360-front-end

https://together.jolla.com/question/...post-id-139893