We mentioned in our‘Introduction to SIP’that SIP excels at accomplishing certain tasks, one of which is locating and initiating sessions with call participants regardless of where they are or what device they are using. How does it do this?
SIP is to VoIP as SMTP is to Email
Locating call recipients and talking with them on their different user agents is accomplished using a SIP address. You can think of a SIP address as an email address that allows you to access your real time IP communications. In fact, SIP addresses are often indistinguishable from email addresses.
SIP addresses are used to find the user’s network location so that they can be reached anywhere. You can think of SIP addresses as being registered to their users, and not to any of their different devices. The adoption of SIP addresses will hopefully spell an end to contact information that only corresponds to a specific device or location.
Imagine for a second that you live in a word where you can only access your work email from your desk computer, and your personal email from your computer at home. Kind of silly, isn't it? Unfortunately, this model is a lot like what you are getting with traditional telephone numbers.
With SIP addresses, you can have one contact ‘number’--so to speak--that follows you wherever you go. I can easily register my desk phone, home phone, and even iPhone, and be reachable on any of my devices when someone dials my SIP address.
You can even take it a step further. OnSIP allows up to 10 device registrations per user at no additional cost.
