Whether you use landlines or handsets, you can’t operate a business without the internet. Instead of paying twice, you can cut down on calling costs by using VoIP. All you need is to configure your desk phones with VoIPSIP, and you’re ready to go. This system is flexible, reliable, and easy to configure. Upgrade to VoIP today and enjoy many more benefits.
https://speakspace.com/blog/how-does-a-voip-phone-system-work