Home > Lync > Cisco Gateway Integration with OCS (180 Ringing Issue)

Cisco Gateway Integration with OCS (180 Ringing Issue)

OCS 2007 R2 utilizes 183 SDP instead of 180 Ringing and therefore causes certain gateways including the Cisco 2800 (2811, 2821, 2851) ISRs to fail if running 12.4(22T) or before. I have not seen an update to OCS or the Cisco code to fix this yet so I am posting this again for reference on this site.

The following file should be saved as RespondWithRinging.am and placed in a location on your FE server. Replace the lcappUri with a more appropriate domain name. This then can be added to the Front End Scripts on each front end server as shown in the image below.

<?xml version=”1.0″?>
<lc:requestFilter methodNames=”INVITE”
domainSupported=”true” />
<lc:responseFilter reasonCodes=”NONE” />
<lc:proxyByDefault action=”true” />
<lc:scriptOnly />

// This script will respond to incoming INVITEs from
// the mediation server.

// Build the user@host from the To: header.
toUri = GetUri( sipRequest.To );
toUserAtHost = Concatenate( GetUserName( toUri ), “@”, GetHostName( toUri ) );

Log( “Debug”, false, “RespondWithRinging: we have a request: “, sipRequest.Method, ” “, toUserAtHost );

// Check if this is a re-INVITE and exit if so
foreach ( sessionExpires in GetHeaderValues( “Session-Expires” ) ) {
if ( ContainsString( sessionExpires, “refresher”, true ) ) {
Log( “Debug”, false, “RespondWithRinging: * skipped; This looks like a session refreshing re-invite” );

// Check to make sure that the INVITE is from a mediation server
foreach ( userAgent in GetHeaderValues( “USER-AGENT” ) ) {
if ( ! ContainsString( userAgent, “mediation”, true ) ) {
Log( “Debug”, false, “RespondWithRinging: * skipped; not a mediation server request” );

// If we’re here, send a 180 response
// Headers are being added in case it’s important to detect this generated 180 response in a log
Log( “Debug”, 1, “RespondWithRinging: * Ringing response being submitted” );
AddHeader( “FAKED-180”, “true” );
Respond( 180, “Ringing”, “FAKED-180=true” );


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