asterisk users - May 2010 - Extension state can get stuck in 'Ringing' state

Hi,
I've noticed that if a phone goes UNREACHABLE while it is Ringing,
when the phone comes back, Asterisk will not clear the channel that
was created, so it still thinks it is in the Ringing state.
The only way to clear this is to do a soft hangup on the SIP channel
or to restart Asterisk.

Unfortunately these issues are very hard to automatically track down
and clear and it seems like if a phone goes UNREACHABLE, Asterisk
should clear the channel anyways.

This is at 1.4.26.2. I'm planning to upgrade to 1.4.31 shortly. I will
see if I can replicate the problem in that version as well.
Has anyone else noticed this?

Thanks.

-- James