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New Member

SIP device dialing timeouts

Hi Guys,

We use 5 digit extensions.  We have third party sip devices registered as extensions in CUCM.

If a user dials an incorrect extension - say 123 (too slow dialing etc), instead of 12345 we get odd behaviour.

With a skinny phone we get audio notification straight away that call failed.

With SIP phone, we get 10 secs of silence before phone gets 404 not found error.

I wish to get rid of the 10 secs of dead air.  Debug below.  Maybe the CUCM is waiting for more digits ?

- > invite 123@

<- 100 trying

<- 183 session progress

10 secs silence

<- 404 not found

-> ack



SIP device dialing timeouts


What is the value in T302 Timer?

This may be due to the SIP phone is using Keypad Markup Language (KPML) and it send number digit by digit. So you will have to reduce T302 timer to get this resolve.


Ronak Patel

Regards Ronak Patel Rate all helpful post by clicking stars below the answer.
New Member

SIP device dialing timeouts

Hi Ronak,

Thanks for the reply. T302 value is 5secs

This is an interesting problem.  Most of the documents talk about delay between end of dialing and sending the SIP invite.  I'm not concerned about that.

I have looked into KPML and don't believe this used by the SIP device. 

It appears this behaviour sends digit by digit via SIP notify.  The capture doesn't show this happening.  All digits are sent at once during SIP invite.

I also investigated the SIP dial plan.  It looks like you would configure this on the CUCM but the actual processing is done on the phone (via downloading dialplan.xml). 

My problem still exists, phone sends a number to CUCM that doesn't match a valid extension or route pattern, and it takes 10secs to get a response.

References -


SIP device dialing timeouts


SIp Dial Rules are only for Cisco SIP Phones and will not work with third party SIp phones.


Ronak patel

Regards Ronak Patel Rate all helpful post by clicking stars below the answer.