The International Telecommunications Union (ITU) announced that there are now 4 billion "phone lines" in the world, which is an extremely impressive number of anything. However, let's look more closely at what constitutes a phone line for the agency: The total number includes both wireline connections (more than 1.2 billion) and wireless accounts (more than 2.6 billion).
We're not trying to split hairs here. This is positive news for the world, and especially for the developing countries where most of the new growth is occurring. The number is a bit clouded by the fact that many households or individuals have more than one wireline or wireless connection, so it's not a true measure of teledensity. It also goes to show that "phone line" is a very ambiguous term. Wireless connections are far outpacing wireline ones worldwide, and we can only count on more of that in the future. The Associated Press has the story on the ITU's count.