It works this way: Your computer (or special external phone) connects to the Internet using an app. When someone calls your business number, the computer or special phone rings. You can have voicemail, multiple lines, etc.
Sorry I wasn’t able to take your call, but please leave your name and a detailed message and I’ll get back to you.

check words for the English /oʊ/ vowel. Many non-native speakers make this more like a single vowel and it’s a double vowel so it should have /o/ and /ʊ/ smoothly joined together. Check it in the word ‘phone’ . Another double vowel to look out for in your Voicemail Greeting example is the diphthong vowel /eɪ/. This vowel is in words like ‘wait’ and ‘able’. Many people use the word ‘can’t’ in their Voicemail greeting example. This can be a trap for non-native English speakers. That’s why we chose ‘unable’ instead! Watch out for the word ‘can’t’! In American English and British English the vowel in ‘can’t’ is pronounced with the vowel /æ/ like in ‘pat’ – /kænt/.
– Thanks for calling. This is (name). Today is a Friday and I am working from our corporate office. If you need to reach me immediately, please call (number). Otherwise, please leave me a message and I’ll return your call as soon as possible.