Hi Pete,
Reference:
http://www.cisco.com/en/US/docs/ios/voice/cube/configuration/guide/vb_1380_ps5640_TSD_Products_Configuration_Guide_Chapter.html
The following sample output shows that the time interval between consecutive NOTIFY messages for a telephone event is the default of 2000 ms:
Router# show sip-ua status
SIP User Agent Status
SIP User Agent for UDP : ENABLED
SIP User Agent for TCP : ENABLED
SIP User Agent bind status(signaling): DISABLED
SIP User Agent bind status(media): DISABLED
SIP early-media for 180 responses with SDP: ENABLED
SIP max-forwards : 6
SIP DNS SRV version: 2 (rfc 2782)
NAT Settings for the SIP-UA
Role in SDP: NONE
Check media source packets: DISABLED
Maximum duration for a telephone-event in NOTIFYs: 2000 ms
SIP support for ISDN SUSPEND/RESUME: ENABLED
Redirection (3xx) message handling: ENABLED
----------------------
Didn't find any modifications required from your config, wondering what is the issue here.
Hope it helps.
Anand
Please rate helpful posts !!