Those voices have mostly come from families in Jordan, India, Pakistan, and other countries in the Muslim world and Asia. Usually, those kidnapped were drivers or lower-level employees of companies doing nonmilitary work under contract to U.S.-led forces in Iraq.
But over the past couple of weeks, the nature of the hostage-taking has changed. Increasingly, it appears, more Westerners are being targeted. Three of the most recent hostages were displayed this week in a video on a militant website. Jack Hensley, Eugene Armstrong, and Ken Bigley worked installing and furnishing camps at the coalition's Taji base.
Hensley and Armstrong are American contractors. Bigley is a British engineer. All three men were kidnapped last week in a dawn raid by unidentified armed men who broke into the house where they were living in central Baghdad.
The kidnapping of the three was the second attack this month on Westerners residing in the capital. Gunmen seized two female Italian charity workers -- Simona Pari and Simona Torretta -- and their Iraqi aides in a daylight attack on their central Baghdad office two weeks ago.
Since the seizures, the hostages' families have appealed for their release. Several have said their relatives were working in Iraq out of a genuine interest in helping the country.
"His love of the area is what has kept him there for so many years and the reason he was prepared to help in Baghdad where many others would have been too worried about their own safety. He wanted to help the ordinary Iraqi people and he is just doing his job," said Phillip Bigley, Ken's brother.
But so far, the pleas have received no response from the group that has claimed responsibility for the kidnappings of the Americans, Briton, and Italians, as well as two French journalists taken last month.
That group is Tawhid and Jihad. It is led by Jordanian-born extremist Abu Musab al-Zarqawi -- whom U.S. officials say is associated with Al-Qaeda.
The group threatened over the weekend to execute the two Americans and the Briton within 48 hours unless the U.S. frees unspecified female Iraqi prisoners.
A spokesman for the U.S. military, Lieutenant Colonel Barry Johnson, says that American forces are not holding any women and that "the only females we hold are two high-value detainees."
The two "high-value detainees" are believed to be female scientists who worked in weapons of mass destruction development programs under Saddam Hussein.
In the wake of the recent kidnappings of Europeans and Americans, all of the hostages' governments have vowed not to be intimidated by the attacks.
British Prime Minister Tony Blair said yesterday that the hostage takers hope to stop Iraq's transformation into a stable, more democratic society -- but will be defeated.
"The people that are trying to stop that Iraq coming about -- who are engaged in kidnapping and killing and murder and acts of terrorism -- are opposed not just to the new Iraq that could take shape, but are opposed to every single one of the values that we in countries like this hold dear."
Blair spoke during a joint press conference in London with visiting interim Iraqi Prime Minister Iyad Allawi.
Still, the widening abductions in Iraq have forced most foreign NGOs and some business firms to withdraw from the country.
Joost Hiltermann is regional head for the International Crisis Group in Amman. He says the foreign staff of most NGOs -- apart from those in the Kurdish-controlled north -- have now left Iraq.
"NGOs have withdrawn, especially after the kidnapping in broad daylight from their office of the two Italian aid workers and their Iraqi aides and many [NGOs] have withdrawn to Jordan, where already a number of NGOs have been based since the situation deteriorated in April. And they are now operating their activities by remote control, using their Iraqi staff to the extent that they are able to move at the moment."
Hiltermann says that some regional companies -- particularly those engaged in transportation -- also have withdrawn from Iraq, sometimes in deals to secure the release of their drivers. But he says that most companies continue trying to work in the country because the potential profits are too great to resist.
"By and large, the sums of money to be gained are so high, the business in Iraq is still so lucrative, that many companies will stay. Obviously, part of their profits will go to security guards to protect their convoys and their facilities. And so a number of contractors are able to stay simply because they feel sufficiently protected still where they are. And they don't venture out too much and when they do they go in heavily armed convoys. Some of the U.S. contractors, for example, now are spending up to 25 percent of their contract on security."
Since the wave of kidnappings began in April, more than 100 foreigners and countless Iraqis have been abducted. Many hostages have been freed, some for ransom, but at least 30 foreign hostages have been killed.
The wave of kidnappings this week also extended to Iraq's security forces as one Islamist group claimed to have taken 18 soldiers captive in an attack on the National Guard.
The group displayed its uniformed captives in a video and threatened to kill them unless the Iraqi government frees an aide to radical Shi'a cleric Muqtada al-Sadr.