By default the English language voice prompts that Asterisk comes with have an American accent. There are some free UK voice prompts available and below are instructions for downloading and installing those. The instructions below will replace the existing US prompts with the UK ones.
The prompts can be found here – https://hellocomtec.com/sounds
The commands below download the wav, ulaw, alaw, g729 and g723 codec versions.
First create a folder to download the files to –
cd /usr/src
mkdir uk
cd uk
next grab the files –
wget https://hellocomtec.com/sounds/Alison_Keenan-British-English-sln.tar
wget https://hellocomtec.com/sounds/Alison_Keenan-British-English-alaw.tar
wget https://hellocomtec.com/sounds/Alison_Keenan-British-English-g723.tar
wget https://hellocomtec.com/sounds/Alison_Keenan-British-English-g729.tar
wget https://hellocomtec.com/sounds/Alison_Keenan-British-English-ulaw.tar
next extract the files that were downloaded –
find . -name 'Alison_Keenan-British-English-*' -exec tar xvf {} \;
now we’re going to replace the file extensions on some of the files to match the default Asterisk ones –
find . -exec rename .g711a .alaw {} \;
find . -exec rename .g711u .ulaw {} \;
now remove the original tar files, copy over the new files and tidy up the download folder –
rm -f Alison_Keenan-British-English-*
unalias cp
cp -rf * /var/lib/asterisk/sounds/en
cd ..
rm -rf uk
That's it!