1* REGISTER transactions:
2  Currently siproxd does only support *one* Contact header in REGISTER
3  transactions. If an UA does send multiple (which is legal) funny things
4  may happen.
5  There are one or two funnies associated with REGISTER transactions that
6  should be mentioned:
7  1)	There can be multiple Contact URIs in the request.  It is legal
8 	(although very rare) to register multiple extensions at the same
9	time.
10 	When multiple extensions need to be registered, they are generally
11 	registered separately.	You probably don't need to worry about this
12 	for the time being, but it is probably worth bearing it in mind.
13  2)	There can be multiple Contact URIs in the response.  If more than
14	one UA has registered for the same AOR, then the response to the
15	REGISTER will contain all the registered AORs and their current
16        expiry times.
17 	None or some of these may need 'unmapping'.  Again, this probably
18 	isn't something you will come across that often, but knowing it can
19 	happen may save you some debugging time later.
20  3)	The Contact in the request may contain '*'.  This is used by some
21 	phones to deregister all registrations for the specified AOR.
22  4)	Sometimes, there is no Contact in the request.  This happens when
23 	a UA is querying the registration database.  This is sometimes used
24 	for diagnostic purposes, although I suppose a phone could do this
25 	automatically for some reason.
26  5)	The definitive expires time is not found in the request.  This is
27 	simply a suggested value.  The actual value is in the response from
28 	the registrar.
29  For the definitive description -> RFC3261 section 10.
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