REQ: Sensitivity improve

I have a mobilephone , its housing is made of AL-Mg Alloy for solidity . but its sensitivity is bad on radiation mode , it;s only -95dbm on GSM and -99dbm on DCS/PCS . could you tell me how to improve it.?The materials of Al-Mg Alloy cause the sensitivity get bad, i guess. Could i get some suggestion from you on pratice, thks?

the house may worse your VSWR of your mobilephone,y can test it with the VNA ,then modify the input match with a capacitor

The material of the case can desense the mobile radio, and more than this even the paint color of the case can affect the performances. For example shall be careful using colors having oxide pigments, as red color (iron oxide) or white color (zinc oxide).
http://www.encyclopedia.com/html/z1/zincoxid.asp
http://minerals.usgs.gov/minerals/pu...ty/iron_oxide/
Desense is happened usually when the case change the path of ground currents of the antenna, or is making the coupling of the digital noise from the board direct to antenna.

Is there any effective method or way to improve the desense ?