Patent Application
20090103519
The present invention relates to a method for switching invite messages and subsequent messages in a softswitch.
The softswitch is used to control connections at the junction point between circuit and packet networks. The softswitch is a central device in a communication network which connects calls from one communication line to another. The switching takes place by means of software running on a computer system.
For establishing a session between an inviting party and an invited party a signalization procedure is processed before the user data can be transmitted between these parties. The protocol which is used for initiation a session is called SIP (session initiation protocol). In SIP an inviting party sends an invite message to the softswitch and the softswitch executes then the signalization procedure. If too many parties generate signalization traffic, the softswitch may also discard bye messages, which in turn is inefficient concerning the handling of session resources. I.e., session resources could be released but are not released because the bye messages have been discarded.
One object of the invention is to provide a method for switching invite messages and subsequent messages in a softswitch with which it is made sure that also during huge signalization traffic the processing of messages related to existing sessions is assured.
An overload because of too many incoming requests should not lead to a degradation of the performance the softswitch. This means, that new call requests should not prevent call release messages from being processed by the softswitch.
According to one aspect of the invention, the object is achieved by a method for switching invite messages and subsequent messages in a softswitch with the features of the independent claim 1.
The method according to the invention for switching invite messages and subsequent messages in a softswitch comprises the following steps. The invite messages are directed to a first list and the subsequent messages are directed to a second list, whereas the subsequent messages of the second list are processed with a higher priority than the messages of the first list.
Advantageous further developments of the invention arise from the characteristics indicated in the dependent patent claims.
Preferably, in the method according to the invention the messages of the first list are processed, if the second list is empty.
Advantageously, in the method according to the invention the invite messages are directed by an inviting party to a first port of the softswitch, and the subsequent messages are directed by the inviting party to a further port of the softswitch.
An embodiment of the method according to the invention comprises the following step. After the softswitch has received an invite massage from the inviting party, the softswitch transmits a message to the inviting party indicating that the subsequent messages shall be send by the inviting party to the further port.
In another embodiment of the method according to the invention the subsequent message of the second list is added to the first list, if the subsequent message does not relate to an accepted session.
Furthermore, in the method according to the invention the subsequent message can be an acknowledge, bye, option or a cancel message.
For solving the object of the invention it is suggested that reading from the first list or the second list is executed by a session initiation protocol machine.
In a further embodiment of the method according to the invention the softswitch uses the session initiation protocol SIP.
Furthermore, a computer program element can be provided, comprising computer program code for performing steps according to the above mentioned method when loaded in a digital processor of a computing device.
Additionally, a computer program product stored on a computer usable medium can be provided, comprising computer readable program code for causing a computing device to perform the mentioned method.
The invention and its embodiments will be more fully appreciated by reference to the following detailed description of presently preferred but nonetheless illustrative embodiments in accordance with the present invention when taken in conjunction with the accompanying drawings.
The figures are illustrating:
The invention makes sure that VoIP SIP signaling messages related to an existing call, which is also referred to as accepted call, are processed before new calls are accepted.
In
In
The second party U2 is hereinafter called invitee, invited user or called party. The called party U2 is the party that receives an invite request for the purpose of establishing a new session. The called party retains U2 this role from the time it receives the invite request until the termination of the dialog established by that invite request.
To establish a call, the caller U1 transmits in a first step 1: an invite message to an IP list port x. Port x forwards the invite message to a first list, which is called input list for invite messages IL. In general, the invite message is a request to invite a user or a service to a new session or to modify parameters of an established session. In
It should be noted that the expression call is an informal term that refers to some communication between parties, and also for the purposes of a multimedia conversation.
A message is data, which is sent between SIP elements as part of the session initiation protocol. A SIP message is either a request from a client to a server, or a response from a server to a client.
A session is hereinafter a set of multimedia senders and receivers and the data streams flowing from senders to receivers. A multimedia conference is an example of a session. A session as defined for the session description protocol (SDP) can comprise one or more real-time trans-port protocol (RTP) sessions. A called party can be invited several times, by different calls, to the same session. If the session description protocol (SDP) is used, a session is defined by the concatenation of the SDP user name, session id, network type, address type, and address elements in the origin field. Further information about SDP can be found in RFC 2327 and in the Internet under the link http://www.ietf.org/rfc/rfc2327.txt.
In addition to the input list for invite messages IL the softswitch 1 comprises furthermore a second list, called input list for subsequent messages SML. Subsequent messages can be for example an acknowledge message, a 200-ok message, a cancel message, an option message, or a bye message.
The acknowledge message ack confirms that the session is established. The cancel message cancels a pending request. The bye message indicates the end of a session. The option message requests information about the capabilities of a server.
Before the softswitch 1 reads the input list for invite messages IL it checks whether the input list for subsequent messages SML is empty. If the input list for subsequent messages SML is not empty and the message stored in the input list for subsequent messages SML is not related to an accepted call, the SIP machine 2 of the softswitch 1 adds this message to the input list for invite messages IL. Afterwards the SIP machine 2 checks again if the input list for subsequent messages SML is empty and if applicable adds this further message to the input list for invite messages IL. In the case, the input list for sub-sequent messages SML is not empty and the message in input list for subsequent messages SML relates to an accepted call, this message is processed. These steps are repeated until the input list for subsequent messages SML is empty. The processing of the messages takes place in a call processing engine 3. If the input list for subsequent messages SML is empty, the input list for invite messages IL is read and the corresponding new call is started. Starting a new call takes also place in the call processing engine 3. The call processing engine 3 sends a message 200-ok . . . contact: SIP: . . . port y back to the inviting party U1, indicating that the invite message has been received and that subsequent messages, e.g., acknowledge, cancel or bye, shall be send from now on to another port y of the softswitch 1.
In
Now, the signaling is so far completed, the session is established, and the transfer of user data can start. The transfer of the user data can be done with the real-time transport protocol (RTP), which is controlled by the real-time transport control protocol (RTCP). The user data are transmitted in data packets on various ways, which are not controlled by the softswitch 1.
If the calling party U1 wants to terminate the session with the invited party U3, the calling party U1 sends a bye U3 message via port y to the input list for subsequent messages SML. In the example the calling party U1 wants to call instantaneously hereon a party U2, whereas the bye U3 message is still stored in the input list for subsequent messages SML and has not yet been processed. Therefore, the input list for subsequent messages SML is not empty, indicted in
Having illustrated and described a preferred embodiment for a novel method for switching invite messages and sub-sequent messages in a softswitch, it is noted that variations and modifications in the method can be made without departing from the spirit of the invention or the scope of the appended claims.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2006/004599 | 5/16/2006 | WO | 00 | 11/16/2007 |
| Number | Date | Country | |
|---|---|---|---|
| 60682136 | May 2005 | US |
