[Serusers] SIP call hold/unhold

[tcchan]

Dear All,

I encountered a UA that behave as follow:

UA1 call UA2

UA1 ---- invite with SDP -----> UA2

UA1 <------OK with SDP --------UA2


UA1 hold the call,

UA1 ------invite (hold)  ------>UA2
UA1 <--------OK but not SDP ---UA2


UA1 unhold the call

UA1 ------invite ----------->UA2
UA1 <-------OK but also no SDP---UA2



I found that most ATA(UA) would attached a SDP when reply an OK whether
the call is hold or unhold.  But there is one ATA that does not (UA2).


I noticed that some ATA--Linksys (UA1) would send a BYE to UA2 if it
receive a OK with no SDP in the hold case.

My Question is :

Is UA2 behave according to RFC?



Would deeply appreciate if someone could let me know the answer as I
always have trouble reading RFCs...


Thanks fot any help available.

Regards,

TC Chan