Re: how I can chnage my lumia 925 rom from rm-910 to others to get LTE support?
The RM-910 is a special variant added for China.
China (and some other APAC countries) use a different LTE standard from the Western countries. In China LTE is FD (Field Division) and in other parts of the world the standard for LTE is TD (Time Division)...
For that reason, LTE was disabled via firmware on the RM-910 as the hardware does not support FD-LTE only TD-LTE...
So far, so good for your cause.
However, we have a split in what can be done with this info.
Based on spec... The RM-910 uses the same UMTS (3G) radio as RM-893 for the Americas... Based on that (and this is only educated guesswork) you could theoretically apply an RM-893 ROM and enable TD-LTE Bands 2, 4, 5, 17.
I would tend to believe the SOC will support only one style or the other of radio so that if you need Euro type LTE Bands they may not be available on the SOC.
Not knowing what country you are in, I can not say if this works for you or not...
The whole concept may or may not work. There are no guarantees of anything except that the procedure is risky. Cross flashing to another variant is always hazardous.
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The process isn't very hard, but I would still recommend you to do some homework before going through 
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