Dialogic 05-2239-009 User Manual

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Dialogic Corporation

In this scenario, the transport protocol of an initial INVITE is TLS and Global Call acts as TLS 
client and server. Global Call will always use a “sips:” URI as the local contact URI unless the 
application specifically changes it, which means that the subsequent incoming request message 
should use TLS because the local URI is “sips:”.

The following figure illustrates a scenario where all transactions are TLS because both the source 
address and destination address are “sips:” URIs.

After the initial INVITE transaction, the transport of subsequent request message to the remote UA 
depends on the Contact URI scheme from the remote response or request messages. This means 
that the remote UA has the freedom to change the Contact URI to be either a “sip:” or “sips:” URI 
independent of initial INVITE request. Global Call will try to use the required transport depending 
on the remote Contact URI scheme in conjunction with default transport protocol and any 

INVITE sips:friend@remote.com SIP/2.0
To:<sips:friend@remote.com>
From:<sips:user@local.com>
Via: SIP/2.0/TLS xxxxxx
Contact: <sips:user@local.com>

200 OK
To:<sips:friend@remote.com>
From:<sips:user@local.com>
Via: SIP/2.0/TLS xxxxxx
Contact: <sips:friend@remote.com>

ACK
To:<sips:friend@remote.com>
From:<sips:user@local.com>
Via: SIP/2.0/TLS xxxxxx
Contact: <sips:user@local.com>

200 OK
From:<sips:friend@remote.com>
To:<sips:user@local.com>
Via: SIP/2.0/TLS xxxxxx

GCEV_DROPCALL

GCEV_RELEASECALL

gc_ReleaseCall()

gc_DropCall()

GCEV_CONNECTED

gc_MakeCall()

destination.address = 

"sips:friend@remote.com"

origination.address = 

"sips:user@local.com"

With TLS client and server configuration.

gc_Start()

With TLS client and server configuration.

gc_Start()

GCEV_OFFERED

gc_Answer()

GCEV_ANSWERED

gc_DropCall()

GCEV_DROPCALL

gc_ReleaseCall()

GCEV_RELEASECALL

GCEV_DISCONNECTED

BYE
From:<sips:friend@remote.com>
To:<sips:user@local.com>
Via: SIP/2.0/TLS xxxxxx