The collapse of traditional channels of communication in Haiti has again highlighted the role of social media and the internet in disasters.
Twitter is being used as a prime channel for communications, while sites such as Ushahidi are providing maps detailing aid and damage.
Both Google and Facebook are producing missing persons lists.
Satellite networks are also diverting resources to provide communications to aid agencies and the military.
The very first images to escape from the region after Tuesday's earthquake came from citizens, capturing video with mobile phones.
But landlines near the epicentre have been wiped out, and mobile phone service has been at best intermittent - a fact that has already hampered rescue efforts.
The UN body Telecoms Sans Frontieres, which maintains a network of telecommunications engineers and mobile equipment worldwide, has deployed two teams in the region. The World Food Programme operates a similar service .
"When we arrive in the country, we establish a telecoms centre for the humanitarian community, for them to be able to communicate and have access to internet and phone," said Telecoms Sans Frontiere's Catherine Sang.