Extra mobile capacity will be brought to the popular coastal location of Selsey in anticipation of a bumper ‘staycation summer’.
Upgrades to the 4G network are due to be completed in the town over the 'next few months'.
A spokesperson said: "The extra mobile capacity will bring better coverage and increased speeds in high-demand areas.
"Mobile users will have better signal to make calls from these locations and faster data speeds to access the internet and apps."
The enhanced 4G coverage forms an 'integral part' of Britain’s Emergency Services Network (ESN), which is already providing 'critical communications' for some first responder and emergency agencies. This allows them to stay connected whilst they fulfil their vital public safety roles.
As the RNLI prepares for an 'exceptionally busy summer', visitors to coastal areas are being encouraged to plan their trips and access beach safety advice online.
The RNLI has also provided advice on how people can use their mobile phone to stay safe while visiting the coast.
Important information on where people can find their nearest lifeguarded beach, what dangers they could face, and what to do in an emergency can be found by visiting: rnli.org/beachsafety.
Marc Allera, CEO Consumer Division at BT, said: “With many popular seaside locations expecting a busy summer, we’re pleased to be providing improved coastal connectivity.
“The upgrades to our network will help ensure our customers stay connected this summer, even at the busiest times.
"The additional capacity delivered through improvements to our 4G network, alongside the continued roll-out of our 5G network, will help people make the most of their time at the coast, and also provide a valuable lifeline, if an emergency occurs.”
Guy Addington, RNLI Regional Water Safety Lead for the South East, said if people follow key safety advice, 'they can stay safe and enjoy their time at the beach and along our coastlines'.
“Alongside our lifeboat crew and lifeguards, mobile phones can help people stay safe when at the coast, so improvements to coastal coverage is welcomed," he added.
"Smartphones can help people plan their day at the coast and check things like the weather, tide times and where our lifeguards are patrolling. Mobiles also allow people to call for help quickly in an emergency situation.
“Whether you’re walking along the coast, angling from rocks, or relaxing on the beach, having the means to call for help in an emergency can be the difference between life and death.”
If you’re in an emergency situation or spot someone else in trouble, you should call 999 or 112 and ask for the coastguard
A spokesperson said: "Even if your phone shows no service, try calling 999 or 112 anyway, as in an emergency, your phone will be able to use another phone network.
"You should ensure your phone is fully charged before heading out, and might want to take a portable charger and keep your mobile in a waterproof pouch and within reach."