Whereas advanced countries are reluctant to replace their entire telephone systems, many developing countries, such as Gambia, are installing digital networks using the latest fibre-optic technology.

• 因为在发达国家还不愿意更换他们全部电话系统时，而很多发展中国家如冈比亚正在安装着使用了最新光纤技术的数字网。