1. A method of operating a first mobile communications device to communicate advertisements, the method comprising: storing a plurality of advertisements and corresponding target audience constraints in said first mobile communications device; receiving a signal from a second mobile communications device; updating information, stored in said first mobile communications device, about a currently reachable target audience based on information included in the received signal; determining, in said first mobile communications device, based on the updated information about a currently reachable target audience, if a target audience constraint corresponding to one of said plurality of advertisements is satisfied, said target audience constraint being one of a device type constraint, a minimum number of devices in a transmission coverage area constraint, a gender constraint or an age constraint; and transmitting, from the first mobile communication device, when it is determined that a target audience constraint corresponding to said one of said plurality of advertisements is satisfied, said one of said plurality of advertisements.