I just received an X527 (via Geekbuying) last week, everything is going well with the phone, apart from the dual sim function! 
Both of my sim slots work fine - I have two sims one from Three Mobile and the other from Lebara.
I can put either sim into the phone using either tray and the phone works perfectly.
If I put both sims into the phone the sims will work initially then the Three Mobile sim will lose signal/connection.
It doesn't appear to make any difference which trays are used the Three Mobile sim will always lose connection.
If I put the Three Mobile sim into another phone it works perfectly, only seems to be a problem when I use the two sims on the X527.
Something seems to be stopping the Three Mobile sim working in the dual mode.
I can turn off the Lebara sim and the Three Mobile sim will work fine.
My set up is to use Lebara for data and outgoing calls and the Three sim for incoming calls, generally speaking.
Any ideas?
Both of my sim slots work fine - I have two sims one from Three Mobile and the other from Lebara.
I can put either sim into the phone using either tray and the phone works perfectly.
If I put both sims into the phone the sims will work initially then the Three Mobile sim will lose signal/connection.
It doesn't appear to make any difference which trays are used the Three Mobile sim will always lose connection.
If I put the Three Mobile sim into another phone it works perfectly, only seems to be a problem when I use the two sims on the X527.
Something seems to be stopping the Three Mobile sim working in the dual mode.
I can turn off the Lebara sim and the Three Mobile sim will work fine.
My set up is to use Lebara for data and outgoing calls and the Three sim for incoming calls, generally speaking.
Any ideas?
