Hi, do you guys have this issue? I find that the reception for mobile phones inside the house is very bad. SingTel, StarHub etc… Any idea how to improve reception?

Nothing much you can do on your own about it unless you get the telcos to put an antenna on your roof.

Mobile phone signals depends on the proximity to the cell station and if you're just nice on the boundary of the cell coverage, you will encounter poor receptions. You can always feedback to the telco which you're having issues with and see if they can sort it out.

is the issue just with your phone or your family members as well? if just yourself, maybe try using another phone and test.