[Asterisk-Users] sip qualify=yes interval

[Damon Estep]

In an earlier thread Andrew Kohlsmith enlightened me on the use of
qualify in sip.conf to deal with a peer that is down.

Since then I have been searching for information on how the behavior of
qualify can be tuned.

The wiki is vague on this;

" Syntax: 

  qualify=xxx|no|yes 

where XXX is the number of milliseconds used. If yes the default timeout
is used, 2 seconds. 

If you turn on qualify in the configuration of a SIP device in sip.conf,
Asterisk will send a SIP OPTIONS command regularly to check that the
device is still online. If the device does not answer within the
configured (or default) period (in ms) Asterisk considers the device
off-line for future calls. "

So;
qualify=1000|yes
means query for SIP OPTIONS, then take then unregister the peer if no
response in 1000ms.

But, how do you set/determine the frequency at which a peer is queried?
Does this go on indefinitely after a peer fails to respond to make sure
the peer is re-registered when available again? Can the interval be set
on a per peer basis?

Any documentation on this that you can point me to?
Thx!