Ping is the time it takes to send a packet and return. Jitter is the consistency of that time. High jitter usually results in higher ping causing delays and reducing connection quality
A good jitter speed to shoot for is 30 milliseconds.
The first thing you should do is contact your provider and see if there are any problems causing poor connection. They will be able to help you troubleshoot and develop a plan of action for what to do next.
Yes. Because there are so many variables that go into determining VoIP quality, it is important to use a VoIP test so you can see if you have any problem areas. By testing your internet connection now, you will be able to prevent problems later on.
You should find a quality VoIP provider and go through their process so you have fast and effective communication. They will help guide and set you up so you are good to go.
You should test it several times a day so you have a solid and reliable idea of what you are working with. For best results, test it on multiple days at various times to get a precise measurement.
You should contact your VoIP provider to see what is going on and how you can fix it. If the problem persists, you may have to switch to another provider.