Configuring Your System

timeout defined in RFC 3261. If it is not the last server in the list, the maximum number of retries using the configurable retry timeout is used. For more information, refer to Server <server/> on page A-7and Registration <reg/> on page A-89.

Warning If DNS is used to resolve the address for Servers, the DNS server is unavailable, and the TTL for the DNS records has expired, the phone will attempt to contact the DNS server to resolve the address of all servers in its list before initiating a call. These attempts will timeout, but the timeout mechanism can cause long delays (for example, two minutes) before the phone call proceeds “using the working server”. To mitigate this issue, long TTLs should be used. It is strongly recommended that an on-site DNS server is deployed as part of the redundancy solution.

Hosted VoIP Service

Provider

Call Server 1B

Call Server 1A

DNS Server

Internet

PSTN

Phone Configuration

 

VoIP SMB Customer

SIP Capable Router

Premise

Server2

 

 

`

 

`

PSTN Gateway

 

 

`

 

`

The phones at the customer site are configured as follows:

Server 1 (the primary server) will be configured with the address of the service provider call server. The IP address of the server(s) to be used will be provided by the DNS server. For example:

reg.1.server.1.address="voipserver.serviceprovider.com"

Server 2 (the fallback server) will be configured to the address of the router/gateway that provides the fallback telephony support and is on-site. For example:

reg.1.server.2.address=172.23.0.1

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Polycom SIP 3.0.2 manual Phone Configuration, Reg.1.server.1.address=voipserver.serviceprovider.com