A friend has a gsm/umts repeater 900mhz/2100mhz. Like the one here. http://cukii.com/GSM-3G-Dual-Band-Signal-Repeater-GSM-900mhz-WCDMA-2100mhz-27dBm-GSM-UMTS-3G-Signal-Booster-Full-Kits-Panel-Antenna

From googling, it is to boost mobile phone signal inside buildings.

He doesnt have any test equipment other than dvm and a silly scope, so how can he test it works? Phone signal is perfectly ok in his house.

[Edited on 9/10/16 by 02GF74]

Unless you have an offcom license, then they are illegal in the U.K.

Getting caught operating one is a £5K fine !

Roger