Can one REGISTER request contain multiple Contact Header Fields for a single URI present in To Header Field?

What will be the practical scenario when a UA will try to register multiple cont开发者_StackOverflowact address against its SIP URI?

One SIP device can only register ONE COntact in one REGISTER message. However, if you support the SIP Outbound functions, one device sends at least TWO REGISTER requests over different IP flows, so the proxy has multiple contacts for the same device.

Now, SIP allows for multiple registrations for multiple devices and multiple registrations from the same device.

There's a new standard called GIN, that uses one REGISTER with one contact to register for multiple phone numbers. Still one contact only.

/O

There are many reasons. One might be this:

• You have a main SIP device (your desk phone)
• You have an answering service (your voicemail server)
• You have a mobile SIP device (some handset or other)