COASTGUARD communications were knocked out for more than 24 hours after thieves stole underground cable.
About 250m of carbon fibre cable was taken from the Southampton area late on Tuesday.
The communication at the Lee-on-the-Solent station was severely affected and back-up teams in Dover were needed to listen out for mayday calls.
The cables have been replaced and BT has urged witnesses to come forward.
Volunteers were called in by HM Coastguard during the early hours to sit in stone buildings along the coast with a bank of radios listening for calls.
The theft knocked out communications from St Boniface Down, on the Isle of Wight, to Newhaven, East Sussex.
There was a reduced capability on the Needles aerial site.
More than 100 homes were also left without internet connection and phone lines.
The service was up and running again by 10.30am on Thursday.
Julia Gosling, spokeswoman for the Maritime and Coastguard Agency, said: ‘When the cable was removed it became very obvious to Solent Coastguard that some of their aerials were not able to pick up signal.
‘There is a back-up system that can be put in place.
‘It affected the communications. We wouldn’t want to have to operate like this for very long.
‘It’s not a situation that we would want to deal with for any period of time.’