IP communication provides for device mobility. For example, a residential broadband connection may be used as a link to a virtual private network of a corporate entity, in which case the IP address being used for customer communications may belong to the enterprise, not being the IP address of the residential ISP. Such off-premises extensions may appear as part of an upstream IP PBX. On mobile devices, e.g., a 3G handset or USB wireless broadband adapter, the IP address has no relationship with any physical location known to the telephony service provider, since a mobile user could be anywhere in a region with network coverage, even roaming via another cellular company.
The majority of plans are loaded with a great selection of features that can come in handy when you are making or receiving calls. Many providers offer over 30 features included in the low monthly fees. These include basic call management features such as call waiting, call forwarding, call blocking, caller ID name, do not disturb, and voicemail. More advanced features such as the voicemail to email feature let's you access your messages at anytime, even when you are away from your home, simply by checking your email inbox. Distinctive ringing, additional virtual numbers, and Smartphone Calling App's are other examples of more advanced features that can be useful.
However, VoIP traffic to and from the on-premises systems can often also be sent over secure private links. Examples include personal VPN, site-to-site VPN, private networks such as MPLS and SD-WAN, or via private SBCs (Session Border Controllers). While exceptions and private peering options do exist, it is generally uncommon for those private connectivity methods to be provided by Hosted or Cloud VoIP providers.