In Australian English it’s pronounced with the vowel /a:/ like in ‘part’. Problems arise when people use the /ʌ/ vowel (like in ‘up’) instead of /æ/ or /a:/. If you do this is will sound like the worst swear word in English. Many non-native speakers often pronounce the vowel /æ/ more like /ʌ/ because they don’t have a vowel like /æ/ in their first language. Many speakers of European languages will do this (Spanish speakers and Italian speakers) and also speakers of Japanese and Korean. This problem with /æ/ also means that if you say the word ‘back’ in your voicemail greeting sample, you are likely to pronounce it more like ‘buck’. remember to pronounce word endings in English. Check you aren’t dropping any endings off or mispronouncing them.
Additionally, you will want to close out your voicemail by (re)stating your contact information and name and purpose of your call. This is another little trick of leaving voicemails - people tend to remember the first and last things you say more so than the middle, so by summarizing the important pieces of your message at the end, what you said is more likely to stick.

Leave your name, number, and a brief message, and I’ll call you back immediately. Voicemail Greetings For Business. You’ve reached (insert company name.) All of our team members are busy at the moment, but someone will return your call within (insert timeframe) if you’ll be so kind as to leave your name, number, and a brief message. Hello!
The tone of your voice when leaving sales voicemails is almost as important as the actual words you say. If you obviously sound like a salesman, your message will be deleted before it even ends. You want to speak in a tone of voice thats friendly, confident, and casual—not overly excited, nervous, or desperate-sounding.