gateways, etc. The default router in this case is the IP address of the LAN interface of the
router itself.
• Performs NAT on packets sent from the private network to the public network. This is an
important feature such that recipients of the private packets will perceive them as originated
from a public IP address (the router’s WAN interface) and will therefore return messages to
the proper public IP address and port. Different routers may use different rules for
allocating port numbers at the WAN interface to forward packets from a private IP
phone.
ed to generate billing data per usage of the IP Telephony
will charge a flat fee for unlimited calls between IP Telephony
ber signs up for IP Telephony service, he selects an
PHONE ADAPTER.
e mail(s). The PHONE ADAPTER can indicate the message-waiting
address/port to a public IP address/port. The allocated port number is also used for routing
packets from external IP addresses to a private address. Most routers will accept a number
of static port mapping rules for forwarding packets received on a specific port at the WAN
interface to a specific IP address/port in the private network.
PSTN - VoIP Gateways: These devices are required if user agents are expected to make calls to or
receive calls from the PSTN. Many gateways may be deployed in order to service a wide area.
Gateways also behave like SIP user agents. The proxy server can be configured with cost-saving
rules based call routing information so that it may decide which gateway to use depending on the
destination and the time of the call. The IP Telephony service provider will assign each subscriber an
E164 telephone number so that it may be reached from the PSTN just like any other tele
Billing Servers: Billing servers are us
service. Typically, the service provider
subscribers (on-net-to-on-net calls). Per use or minute chargers will be incurred only when the
subscriber makes calls to PSTN numbers (on-net-to-off-net calls) through one of the PSTN gateways.
CDR (call detail record) data are generated by the PSTN gateway and sent to the billing servers.
Provisioning Servers: Provisioning servers are used to provision the subscriber user agent devices,
e.g. the PHONE ADAPTER. When a subscri
appropriate service level and enters his personal information including billing information. This
information is processed by the provisioning server and stored into the service provider’s customer
database. The provisioning server generates a device profile based on the subscriber’s choice of
options. The device profile, which is list of configuration parameters, is downloaded into the PHONE
ADAPTER from the provisioning server. The PHONE ADAPTER can be configured to contact the
provisioning server periodically to check for any update of the device profile, which may include a
firmware upgrade or configuration modification to the
Application Servers: Application servers are used to provide value added services, such as call
forwarding, outgoing or incoming call blocking
Voice Mail Servers: Specialized servers provide voice mail services to the IP Telephony service
subscribers. When the subscriber is busy or the PHONE ADAPTER is out of service for maintenance
or other reason, incoming calls to the subscriber may be redirected to the voice mail servers where
the caller can leave a voice mail. The voice mail server will then notify the subscriber’s PHONE
ADAPTER of the availability of voice mail(s) in his mailbox. The subscriber can then contact the voice
mail server to retrieve his voic
status to the subscriber through a number of methods such as stuttered dial tone heard through the
telephone every time the subscriber lifts up the handset until the voice mail is retrieved.
1.1.2. Provisioning Overview
The PHONE ADAPTER is configurable in many ways such that it can provide a wide range of
customizable services and operate in many diverse environments with a variety different vendors’ SIP
Proxy Servers, VoIP Gateways, Voice Mail Servers, NAT applications, etc. Provisioning is the
process by which the PHONE ADAPTER obtains a set of configuration parameters in order for it to
operate in the Service Provider’s network.
The complete set of configuration parameters for an PHONE ADAPTER corresponding to an
individual subscriber is referred to as a configuration profile or simply a Profile. The Profile can be
encoded as an XML file or a simple plain text file with a list of tag/value pairs. When the PHONE
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