User's Manual  532  Document #: LTRT-27055 
 
  Mediant 1000B Gateway & E-SBC 
the device attempts to re-route the call to the next proxy destination, and so on until an 
available IP destination is located. To enable the Proxy Redundancy feature for a 
Proxy Set, set the IsProxyHotSwap parameter to 1 and the EnableProxyKeepAlive 
parameter to 1. 
When the Proxy Redundancy feature is enabled, the device continually monitors the 
connection with the proxies by using keep-alive messages (SIP OPTIONS). The 
device sends these messages every user-defined interval (ProxyKeepAliveTime 
parameter). If the first (primary) proxy in the list replies with a SIP response code that 
you have also configured by the 'Keep-Alive Failure Responses' parameter, the device 
considers the Proxy as down; otherwise, the device considers the proxy as "alive". If 
the proxy is still considered down after a user-defined number of re-transmissions 
(configured by the HotSwapRtx parameter), the device attempts to communicate 
(using the same INVITE) with the next configured (redundant) proxy in the list, and so 
on until an available redundant proxy is located. Once an available proxy is located, 
the device can operate in one of the following modes (configured by the 
ProxyRedundancyMode parameter): 
•  Parking mode: The device continues operating with the redundant proxy (now 
active) until the next failure occurs, after which it switches to the next redundant 
proxy. 
•  Homing mode: The device always attempts to operate with the primary proxy. In 
other words, it switches back to the primary proxy whenever it's available again.  
If none of the proxy servers respond, the device goes over the list again. 
 
 
 
Note:   
•  The device assumes that all the proxy servers belonging to the Proxy Set are 
synchronized with regards to registered users. Thus, when the device locates an 
available proxy using the Hot Swap feature, it does not re-register the users; new 
registration (refresh) is done as normal.  
•  You can also enable the Busy Out feature, whereby the device can take specified 
actions if all Proxy Sets of associated destination IP Groups of matching routing 
rules in the Tel-to-IP Routing table do not respond to connectivity checks. For 
more information, see the EnableBusyOut parameter.  
•  If the AltRoutingTel2IPEnable parameter is enabled for the IP Connectivity feature 
(see Alternative Routing Based on IP Connectivity on page 528), the Busy Out 
feature does not function with the Proxy Set keep-alive mechanism (see below). 
To use the Busy Out feature with the Proxy Set keep-alive mechanism (for IP 
Groups), disable the AltRoutingTel2IPEnable parameter. 
 
The following procedure describes how to configure alternative Tel-to-IP routing based on 
SIP response codes through the Web. You can also configure it through ini file 
(AltRouteCauseTel2Ip) or CLI (configure voip > gateway routing alt-route-cause-tel2ip). 
  To configure alternative Tel-to-IP routing based on SIP response codes: 
1.  Configure SIP response codes (call failure reasons) that invoke alternative Tel-to-IP 
routing: 
a.  Open the Reasons for Tel-to-IP Alternative Routing table (Setup menu > 
Signaling & Media tab > Gateway folder > Routing > Alternative Routing 
Reasons > Reasons for Tel > IP).