20
V.
telePHone connectIons
IntroductIon to sIP
SIP (Session Initialization Protocol) is the standard used by VH2 to talk to virtual phone lines. These lines must be
created in some way externally before they are “applied” to VH2. “Applying” SIP lines to VH2 involves configuring
the unit with certain information about the lines and the location of the server that delivers them. Then the unit
can be allowed to register with the SIP server and automatically handle all of the interface with the virtual line
.
The SIP line can be delivered from several sources:
1
A commercial telephony provider that delivers SIP-based lines over a public or private IP
network.
2
A PBX that delivers telephony to extensions via SIP (in this case theVH2 is treated like a PBX
extension).
3
A hardware gateway device designed to bridge legacy telephone services to SIP. These devices
interface to the outside worlds via analog POTS/PSTN cables, T1/E1 circuits, or ISDN. They
interface to VH2 via IP over Ethernet.
The setup and interface are identical for options 1 & 2 and similar for option 3.
The first step in setting up a SIP-based phone line is establishing an account with some kind of SIP-based provider
or PBX. This process can’t be described here, but the result of this process is that you will have access to certain
credentials for that account. These typically consist of:
Server Domain
- The IP address or URL of the server to which you are being registered.
Username
- The name that VH2 will use when logging into the service.
Password
- The password associated with your account for security purposes.
In addition, several SIP providers require an
Authorization Username
, which is often defaulted to be the same as
the username but sometimes is required to be different.
SIP is a complex protocol, and is based on Internet standards documents called RFCs. These documents are often
subject to interpretation, and some PBXs, gateways, or telephony providers may have some obscure SIP settings
requirements to work best with VH2. But most should work with just the credentials noted above.
Once VH2 is set up to work with a PBX or Internet Telephone Provider, it will automatically register with the
correct server and maintain a connection to the server indefinitely. This way, the provider or PBX can notify VH2 of
incoming calls to its phone number, as well as route outgoing calls correctly.
With hardware gateways, the process is reversed. VH2 will actually emulate a SIP server to the gateway device. The
credentials will be entered into the gateway device. VH2 will only need to know the address of the gateway device
Summary of Contents for VH2
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