It may sound silly, but the tone in which you say something can either play the professional status up, or it can bring it down. You can’t change what your voice naturally sounds like, but you can work on controlling it to make sure you sound calm and collected when recording your message.
Example: 'Thank you for calling [insert name here]. We're sorry we couldn't take your call this time. However, if you'd like to leave us a voicemail we will get back to you within [for example] 30 minutes of receiving this message. Alternatively, if you'd like to reach out by email you can do so at [insert email address]. Again, thank you for calling [insert company name]. We look forward to your message.'

Leaving a voicemail can still be a good way to grab the attention of a potential new customer. However, when it comes to leaving a voicemail, you only have a few seconds to actually grab the listener's attention. Most salespeople screw this up by leaving too much information and making themselves sound like a salesperson, which is the kiss of death when leaving a voicemail.
Professional voicemails are important, because they’re an extension of your personal brand, reflecting what level of professionalism you offer. Use these voicemail greetings for work or personal cell phone messages for your specific needs. You can choose a voice that will best suit your business and will deliver a warm and professional voice message. Your callers don’t want to hear a cold and indifferent machine voice. The information you want to put in your voicemail should be succinct enough for your callers to get every bit of information they need. Leave the relevant information in a clear and precise manner. Professional voicemail greetings for work should be informative. The first message the customer hears should have the company’s name so they can be sure they’ve reached the right number. Be courteous and informative. This could be their first point of contact, and you want it to be enjoyable. You may also like 30 Best Wishes and Congratulations for New Business Adventures If you’re going to make your voicemail message humorous in some way, it should be tasteful and aligned to your brand. It shouldn’t get in the way of giving customers enough information when they call. Your voicemail greetings for work should be welcoming and friendly but not too informal. Customers want to feel confident that they’ve contacted a professional, that the company values their call, and they have made the right choice. So be friendly but not too nonchalant. Your voicemail greeting should be clear, concise and to-the-point. You don’t have to put your clients through a sales pitch when they are trying to just get some information.