Cisco Cisco IOS Software Release 12.2(8)T

If there are active calls, the bind command will not take effect if it is issued for the first time or if it is 
issued while another bind command is in effect. A message is printed reminding you that there are active 
calls and that the bind command change cannot take effect.

The SIP Gateway Support for the Bind Command feature has the following benefits:

With the bind command, SIP signaling and media paths can advertise the same source IP address 
on the gateway for certain applications, even if the paths used different addresses to reach the source. 
This eliminates confusion for firewall applications that, prior to the use of binding, may have taken 
action on several different source address packets.

Cisco SIP Proxy Server

Cisco VoIP

The following documents contain information related to the Cisco SIP functionality:

Cisco IOS Voice, Video, and Fax Configuration Guide, Release 12.2

Cisco IOS Voice, Video, and Fax Command Reference, Release 12.2

Cisco IOS IP Configuration Guide,  Release 12.2

Cisco IOS IP Command Reference, Volume 1 of 3: Addressing and Services, Release 12.2

Cisco IOS IP Command Reference, Volume 2 of 3: Routing Protocols, Release 12.2

Cisco IOS IP Command Reference, Volume 3 of 3: Multicast, Release 12.2

SIP call flows are described in: SIP Call Flows, Release 12.2(4)T

, Release 12.2(2)XB

The physical cable is pulled on the 
bound port, or 

the Interface layer goes down

The TCP and UDP socket listeners are initially closed. 

Then the sockets are opened and bound to listen to any address.

When the pulled cable is replaced, the result is as documented for no shutdown 
interfaces.

A bind interface is shutdown, or 

its IP Address is changed, or 

the physical cable is pulled while SIP 
calls are active

The call becomes a one-way call with media flowing in only one direction. It flows 
from the gateway where the change or shutdown took place, to the gateway where 
no change occurred. Thus, the gateway with the status change no longer receives 
media.

The call is then disconnected, but the disconnected message is not understood by 
the gateway with the status change, and the call is still assumed to be active.