Here are some tips to try out if your iPhone voicemail is not working-
Let us start with the basics. In case you have not set up the voicemail do it the first thing. You can check whether or not you have enabled the voicemail by clicking on the Phone app.
You can try to fix this problem by switching on the Airplane mode and then switching it off. If your voicemail is not working because of a problem in the cell network it can be fixed by doing this. Turn the mobile data off and then again you can switch it on. Switch off your phone and then reboot it. A lot of the time simply doing this may fix the problem of your voicemail.The network operators send regular updates. Sometimes, there could be a problem with updating the system. Go to your phone settings and check for updates. If something needs to be updated do it.Changing your password may fix the problem. Go to the Settings in your phone and change the password of your voicemail.
If nothing helps, try resetting the Network settings. Go to settings tap on General and then Reset. You will see Reset Network Settings click on it.
These tips may seem very simple to you but they sure are effective. Voicemail may seem to have disadvantages but it eliminates the need for your continuous presence. It can be great for businesses where customers can call anytime. It means that you can take a breather and you will not lose any customers also.