If you recently restored or updated your iPhone, your network setting may have been affected and may be causing “iPhone voicemail error try again later.” Please reset your network settings. Go to Settings > General > Reset > Reset Network Settings Enter your password. Press Reset network setting in red font. The phone will automatically reset it. After it restarts, your phone then tries voicemail again.
Instead, lead with, "Next time we talk, I want to share two goals on our new product roadmap that speak directly to several pain points you've raised. I'll tell you more in our next meeting. How about next Tuesday?"

As the odds of receiving a call back from your voicemail message are already low, you need to be very specific about what you say in your voicemail to give you the greatest chance of getting a call back. What you absolutely do NOT want to do is make yourself sound like a salesperson making a cold call. Instead, you want to sound like a very confident business colleague who deserves the respect of getting a call back.
A good voicemail greeting is short and professional, lets people know that you’ll get back to them, and invites callers to continue engaging with a call-to-action. You should also show your personality if you’re in an industry or role that allows that. If your industry is more conservative, however, you’ll want to keep humor and personal touches to a minimum. A greeting Your name Your company A simple explanation for missing the call (e.g. you’re away from the phone or are on holiday) A rough estimate of when you’ll get back to the person An alternative person to reach out to (if you’re out of office) An alternative mode of communication (if you prefer email or text) A call-to-action such as “Leave a message” or “Send me an email at [email protected]”