Holding your phone to your right ear with your right hand is likely to give you better reception, according to a Danish study.
The Nordic Council of Ministers commissioned Aolborg University to analyse how effectively different smartphones received and sent radio signals.
In modern smartphones, the antennas that enable the devices to work wirelessly are buried within the body.
The hidden antenna means users are unaware of its location, and therefore are unable to keep it away from impediments.
To test the strength of each phone, Professor Gert Frølund Pedersen placed them in a testing space that could measure signal strengths along with a mannequin.
Overall, Mr Pedersen found the right hand and right ear makes for a stronger connection with less obstruction.
iPhones are the poorest at transmitting signals for phone calls regardless of the hand used, but are particularly bad when held in the left hand and pressed to the left ear.
This could be a result of the left-left combination obstructing the iPhone antenna, or purely that the iPhone antenna is worse than other phones.
Tests for data services found it did not matter which hand the phone was held in, as users would not have the additional barrier of the head.
However, iPhones still performed poorly for data services.
Tests on handheld tablets found signal strength was affected by the use of two hands, as opposed to free space.
"For many phones the voice communication performance depends strongly on which side of the head the phone is used," Prof Pedersen concluded.
"Variation among phones for data service is less than for voice service but still significant… The variation in performance is still significant, but not as large as for the voice measurements."