asterisk users - Sep 2014 - weird behaviour of sip history and sip debug

Hi all

  I am using Asterisk 12.4.0 on debian 7.6 x64

  I experience some troubles with some specific calls, so I want to dig 
into this as deep as possible

I run these CLI commands:
 > sip set history on (answer: SIP History Recording Enabled)
 > sip set debug peer 501 (answer: SIP Debugging Enabled for IP: ...)
 > sip set debug peer 502 (answer: same with another IP)

but

when I paste the console session output (I get it from Putty) to a text 
file, it appears that it does not contain anything regarding IP of a 
peer which is RECEIVING calls (501 in this case). Is this expected 
behaviour ? Or is there a setting that manages this output ?

Second, for MOST of the calls (I have had them 50 or more maybe), whose 
call-id I know, sip show history displays:

No such SIP Call ID starting with '...'

Is there a limit on sip history storage ? (this history appears to be 
not very much useful anyway, but I suspect it might be an indicator of 
some more serious problems in my setup)

Many thanks for helping in sorting these out

Yours, Kirill