The mobile phone is celebrating its 25th anniversary in the US. Motorola's DynaTAC 8000X was built by a team headed by Dr Martin Cooper, a general manager for the systems division at Motorola who is widely credited with making the first mobile phone call.

However, for publicity purposes the 'first' call was made on Soldier Field in Chicago by Bob Barnett, president of Ameritech Mobile Communications (now Verizon Wireless). He called the grandson of Alexander Graham Bell.

The DynaTAC 8000X was 10in tall, with a 2in flexible aerial and weighed around 800g. Its red LED screen displayed the number called and SMS was not included.

The handset cost a whopping $3,995 with a $50 per month service charge, and calls cost 40 cents a minute at peak hours and 24 cents a minute off-peak.

Despite the high price, the service had 12,000 subscribers within a year. Today over a billion people use mobile phones.