CN111212192A

CN111212192A - Method and device for playing voice when IMS fixed-line user dials VOLTE user

Info

Publication number: CN111212192A
Application number: CN201811387451.XA
Authority: CN
Inventors: 王冬玲; 邓勇; 吴清育; 王松龙; 蔡珣; 郑志结; 黄凌琳
Original assignee: China Telecom Corp Ltd
Current assignee: China Telecom Corp Ltd
Priority date: 2018-11-21
Filing date: 2018-11-21
Publication date: 2020-05-29
Anticipated expiration: 2038-11-21
Also published as: CN111212192B

Abstract

The invention discloses a method and a device for playing voice when an IMS fixed-line user dials a VOLTE user, and relates to the field of communication. The playback method comprises the following steps: judging whether a call request response message returned by a called side carries early media parameters or not; if the call request response message returned by the called side carries the early media parameter, determining the playback processing mode of the calling side according to whether the called side returns RTP media stream information within the first preset time. The invention can solve the problem that the ring back tone can not be heard by the VOLTE user under the same operator when the fixed telephone user under the IMS domain dials.

Description

Method and device for playing voice when IMS fixed-line user dials VOLTE user

Technical Field

The invention relates to the field of communication, in particular to a sound playing method and device for dialing a VOLTE (voice over long term evolution) user by an IMS (IP multimedia subsystem) fixed-line user.

Background

IMS (IP Multimedia Subsystem) is a new IP Multimedia Subsystem proposed by 3GPP in R5, is a general network architecture for providing Multimedia services over IP-based networks, and can provide converged Multimedia services and internet applications for users using different access means. Voice-over-LTE (Voice-over-LTE, long term evolution Voice bearer) is commonly called high-definition call, and is a scheme for solving Voice under LTE, which adopts an IP data transmission technology, i.e., operates in an IMS system.

The early media playback means that before the called party goes off-hook, the calling party waits for the prompt tone heard by the calling party during the period of the called party going off-hook. For example, the color ring back tone service, that is, when a called party signs a color ring back tone service, a calling party dials a called phone, and before a called party goes off-hook, the calling party hears a color ring back tone prompt tone activated by the called party; for the called party without signing the color ring back tone service, the calling party dials the called phone, before the called party goes off the phone, the calling party determines to play sound locally by the calling side or by the called side according to the media playback parameter indication in the temporary response message, and waits for the called party to answer the phone.

According to the definition of the current RFC5009 standard specification, the early media playback has a Gateway mode and an App mode, and the Gateway mode is adopted in the practical application of three operators in China. The Gateway mode means that the control of the whole early media playback is totally centralized in the network as the network element equipment of the Gateway, so that the terminal can not perceive how many media sources are at the end of the far end. The standard requires that, once the 18-bit message or UPDATE message returned by the called side has a P-Early-Media parameter, it means that the network of the called side provides Media resources, and in practical application of three operators in China, the case that the value of P-Early-Media in RFC5009 is "inactive"/"gated" is temporarily not considered. The P-Early-Media value sendonly (only send) is a general scene.

18, sendonly/sendresv distinction of P-Early-Media and SDP (Session Description Protocol) in information: the header values of sendonly and the like in P-Early-Media in 18 are different from sendonly in SDP, and do not represent the meaning of the transmission/reception mode, and they represent the transmission direction, and sendonly represents the Media from the called side to the calling side, i.e., the backward Early Media. Meanwhile, when the early media header field and the SDP appear simultaneously, no conflict exists, the early media is accompanied by sendonly, the terminal is only told to prepare the RTP (Real-time Transport Protocol) receiving thread of the terminal, the terminal is wanted to send, the sendonly in the SDP is the SDP told to the terminal, and when the terminal is ready to send data, the terminal is processed according to the told receiving and sending mode.

The core networks of fixed-line users and VOLTE users in the IMS domain are both based on an IMS architecture, but the two sets of IMS systems are completely independent. A bearer device (hereinafter referred to as an SIP access gateway) of a fixed-line user in an IMS domain and a VOLTE mobile terminal both integrate an SIP (Session Initiation Protocol) stack, and communicate with an IMS system using an SIP Protocol in the role of an SIP client. As the SIP client, it needs to have playback capability (such as ring back tone, dial tone, congestion tone, hold tone, etc.) according to the protocol requirements.

In the related technology, when a fixed network gateway user initiates a call under the fixed network IMS, the gateway only judges whether 18 messages in the SIP protocol returned by the called side carry SDP with media information. If the 18 message returned by the called side contains SDP with media, before the called side picks up the phone to answer, the gateway side does not play the sound to the calling user, but waits for the sound played by the called side, namely, the back sound played by the called side is transmitted. If the called side returns 18 x without SDP information, the gateway side plays the local ring back tone of the gateway to the calling user before the called side picks up the phone, and the gateway does not judge whether the called side returns 18 x with P-Early-Media. Currently, most gateways adopt the processing mechanism. When the gateway user in the judging mode dials VOLTE users of the same operator who do not sign the called color ring back tone service, the calling user can not hear the ring back tone before the called user picks up the phone to answer the phone.

In the related protocol specifications, there are clear regulations on the playback requirements of the fixed telephone user initiated call under the IMS domain. However, the different network elements have incomplete understanding of the protocol specification, which results in that part of IMS core network elements and the service platform do not completely process the backward playback requirement returned from the called side according to the specification requirement, for example, an individual network element starts a playback scene with P-Early-Media being a gated playback scene, an individual network element does not carry a P-Early-Media header field in 180ringing for color ring playback, and the like. If the gateway strictly processes the playback processing of the early media according to the requirements of the SIP protocol specification, when a fixed telephone user in the IMS domain initiates a call, the calling side can not hear the correct backward playback (such as color ring, ring back tone, abnormal playback, etc.) of the called side under some call scenes. At this time, when the user access gateway in the IMS domain initiates a call, in order to adapt to called users in various forms of the current call network, the user access gateway can only adapt to and meet the requirements of various network elements and various called users for backward playback processing in a maximized manner on the basis of not completely meeting the playback requirements of the SIP protocol specification.

In addition, after the VOLTE user accesses the network, the VOLTE side related network element strictly performs playback processing according to the SIP protocol specification. When VOLTE user without called color ring initiates a call, VOLTE side returns to first 183 SDP header field with Media information and no P-Early-Media header field with Media information of calling side, and does not play ring back tone for calling side. For example, when a fixed network IMS under the same operator initiates a call to dial a VOLTE user without a called ring back tone, the VOLTE side does not play a ring back tone to the calling side at this time, and the calling side cannot hear any sound, because the VOLTE side listens to a ring back tone played by the called side according to the existing processing mechanism of the gateway before the called party goes off-hook to listen.

Disclosure of Invention

The invention aims to solve the technical problem of providing a sound playing method and a sound playing device for dialing a VOLTE user by an IMS fixed-line user, which can solve the problem that the ring back tone can not be heard by the VOLTE user dialing the same operator by the fixed-line user in an IMS domain.

According to one aspect of the present invention, a playback method for an IP multimedia subsystem IMS fixed-line user to dial a long term evolution voice bearing VOLTE user is provided, which includes: judging whether a call request response message returned by a called side carries early media parameters or not; if the call request response message returned by the called side carries the early media parameter, determining the playback processing mode of the calling side according to whether the called side returns the real-time transport protocol (RTP) media stream information within the first preset time.

Optionally, determining, according to whether the called side returns the RTP media stream information within the first predetermined time, a playback processing manner for the calling side includes: if the called side returns RTP media stream information within the first preset time, the called side is transmitted for playing; if the called side does not return RTP media stream information within the first preset time, playing the local ring back tone of the gateway to the calling side.

Optionally, the determining whether the call request response message returned by the called side carries the early media parameter includes: and judging whether the call request response message returned by the called side carries an early media header field or a Session Description Protocol (SDP) header field.

Optionally, the call request response message includes a 180ringing message and a 183session procedure message, and the playback method further includes: if the 180ringing message does not carry the early media header field or the SDP header field, or the early media parameter in the 183session process message is in an inactive state, the local ring back tone of the gateway is played to the calling side.

Optionally, the playback method further includes: and if the 183session process message does not carry the early media header field or the SDP header field, the message is not processed, and 18-times information returned by the called side is received again after waiting for the second preset time.

According to another aspect of the present invention, a playback apparatus for dialing a VOLTE user by an IMS fixed-line user is further provided, including: the early media parameter judging unit is used for judging whether a call request response message returned by the called side carries early media parameters or not; and the playback processing unit is used for determining a playback processing mode for the calling side according to whether the called side returns real-time transport protocol (RTP) media stream information within first preset time or not if the call request response message returned by the called side carries the early media parameters.

Optionally, the playback processing unit is configured to transparently transmit the playback of the called side if the called side returns the RTP media stream information within the first predetermined time; if the called side does not return RTP media stream information within the first preset time, playing the local ring back tone of the gateway to the calling side.

Optionally, the early media parameter determining unit is configured to determine whether a call request response message returned by the called side carries an early media header field or a session description protocol SDP header field.

Optionally, the call request response message includes a 180ringing message and a 183session procedure message, where the playback processing unit is configured to play a local ringback tone of the gateway to the calling side if the 180ringing message does not carry the early media header or the SDP header, or the early media parameter in the 183session procedure message is in an inactive state.

Optionally, the playback processing unit is configured to, if the 183session procedure message does not carry the early media header or the SDP header, not perform processing, and wait for a second predetermined time and then receive the 18 × information returned by the called side again.

According to another aspect of the present invention, a playback apparatus for enabling an IMS fixed-line phone user to dial a VOLTE user is further provided, including: a memory; and a processor coupled to the memory, the processor configured to execute the playback method as described above for implementing dialing the VOLTE user by the IMS fixed-line user based on the instructions stored in the memory.

According to another aspect of the present invention, a computer-readable storage medium is also provided, on which computer program instructions are stored, which when executed by a processor, implement the above-mentioned steps of implementing the playback method for the IMS fixed-line user to dial the VOLTE user.

Compared with the prior art, the access gateway side of the fixed-line user in the IMS domain determines the playback processing mode of the calling side by referring to the transmission condition of the RTP media stream of the called side in the preset time according to the early media parameter carrying condition in the call request response message, and can solve the problem that the ring back tone can not be heard by the VOLTE user dialing the same operator in the IMS domain on the premise of not modifying the existing SIP protocol playback specification and adapting to the playback processing mechanism of the related network element of the current network.

Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.

The invention will be more clearly understood from the following detailed description, taken with reference to the accompanying drawings, in which:

fig. 1 is a flowchart illustrating a playback method for an IMS fixed-line user to dial a VOLTE user according to an embodiment of the present invention.

Fig. 2 is a flowchart illustrating a playback method for an IMS fixed-line user to dial a VOLTE user according to another embodiment of the present invention.

Fig. 3 is a signaling diagram illustrating that a 180Ringing message in a call simultaneously carries a P-Early-Media header field or an SDP header field in one embodiment.

Fig. 4 is a signaling diagram illustrating that a 183Session Progress message in a call simultaneously carries a P-Early-Media header field or an SDP header field in an embodiment.

Fig. 5 is a signaling diagram illustrating that a 180Ringing message in a call only carries an SDP header field in one embodiment.

Fig. 6 is a signaling diagram of an embodiment in which a 183Session Progress message only carries a P-Early-Media header field sendonly.

Fig. 7 is a signaling diagram illustrating that a 183Session Progress message in a call only carries an SDP header field in an embodiment.

Fig. 8 is a schematic structural diagram of a playback apparatus for dialing a VOLTE user by an IMS fixed-line user according to an embodiment of the present invention.

Fig. 9 is a schematic structural diagram of a playback apparatus for dialing a VOLTE user by an IMS fixed-line user according to another embodiment of the present invention.

Fig. 10 is a schematic structural diagram of a playback apparatus for dialing a VOLTE user by an IMS fixed-line user according to still another embodiment of the present invention.

Detailed Description

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings.

Fig. 1 is a flowchart illustrating a playback method for an IMS fixed-line user to dial a VOLTE user according to an embodiment of the present invention. This embodiment may be performed by a gateway.

In step 110, it is determined whether the call request response message returned by the called side carries the early media parameter. Namely, whether the 18-letter information returned by the called side carries a P-Early-Media header field or an SDP header field is judged.

When a fixed telephone user in an IMS domain dials a VOLTE user in the same operator, before a called side is not off-hook to answer, a gateway side receives 18-bit information returned by the called side, and can determine whether to carry a P-Early-Media header field or an SDP header field according to the 18-bit information.

In step 120, if the call request response message returned by the called side carries the early media parameter, the playback processing mode for the calling side is determined according to whether the called side returns the RTP media stream information within the first predetermined time.

For example, if the called side returns RTP media stream information within a preset time, the called side is transmitted for playing; if the called side does not return RTP media stream information within the first preset time, playing the local ring back tone of the gateway to the calling side. The first predetermined time may be set according to actual conditions, for example, set to 3 seconds.

In the embodiment, the access gateway side of the fixed-line user in the IMS domain determines the playback processing mode of the calling side by referring to the early media parameter carrying condition in the call request response message and the sending condition of the RTP media stream of the called side in the preset time, and can solve the problem that the VOLTE user in the IMS domain dialing the same operator cannot hear the ring back tone on the premise of not modifying the existing SIP protocol playback specification and adapting to the playback processing mechanism of the related network element of the current network.

In step 210, when the gateway user hanging down in the fixed network IMS domain makes a calling originating call, the gateway receives 18 information returned from the called side before the called side does not pick up the call.

In step 220, it is determined whether the 18 × information returned by the called side carries a P-Early-Media header field or an SDP header field, if yes, step 230 is executed, otherwise, step 240 is executed.

In one embodiment, as shown in fig. 3, the 180Ringing message in a call carries signaling of a P-Early-Media header or SDP header, where the P-Early-Media header is a sendonly parameter and the MediaAttribute of the SDP header is a sendrecv parameter.

In another embodiment, as shown in fig. 4, the 183Session Progress message in a call carries signaling of both a P-Early-Media header field and an SDP header field, where the P-Early-Media header field is sendonly, and the Media Attribute of the SDP header field is sendtech.

In step 230, it is determined whether the called side returns RTP media stream information within a first predetermined time, if yes, step 231 is executed, otherwise, step 232 is executed.

In step 231, the called side plays the voice. That is, if the gateway receives the RTP media stream information of the called side, the network element corresponding to the called side plays the sound to the calling side. The calling side listens the playback played by the network element of the called side.

For example, as shown in fig. 5, a 180Ringing message in a call only carries a signaling example of an SDP header field, and in about 1 second, the gateway receives an RTP media stream returned from the called side, and at this time, the gateway transparently transmits the sound played by the called side, that is, the calling side hears the sound played in the RTP media stream.

In another embodiment, as shown in fig. 6, the 183Session Progress message in a certain call only carries the signaling with the P-Early-Media header field being sendonly, and within 2 seconds, the gateway receives the return RTP Media stream from the called side, and at this time, the gateway transparently transmits the playback from the called side, that is, the calling side can hear the playback carried in the RTP Media stream.

In step 232, the ringback tone local to the gateway is played to the calling side. For example, if 3 seconds after receiving 18 × early media does not receive the RTP media stream returned by the called side, the gateway side plays the local ring back tone of the gateway to the calling side. The calling side listens the ring back tone played by the calling gateway side.

In an embodiment, as shown in fig. 7, a 183Session Progress message in a call only carries a signaling example of an SDP header field, and if the gateway still does not receive an RTP media stream returned by the called side after more than 3 seconds, the gateway needs to actively play a ring back tone local to the gateway to the calling side.

In step 240, if the 180ringing does not carry the P-Early-Media header or the SDP header, or the P-Early-Media in the 183Session Progress message is in inactive state, the local ring back tone of the gateway is played to the calling side. The calling side listens the ring back tone played by the calling gateway side.

In step 250, if the 183Session Progress message does not carry the P-Early-Media header field or the SDP header field, the process is not performed, and the 18 × information returned by the called side is received again after waiting for the second predetermined time. The second predetermined time may be specifically set according to actual conditions, and in one embodiment, is, for example, 60 seconds.

In an embodiment, if the 183Session Progress message does not carry a P-Early-Media header field or an SDP header field, the gateway needs to wait for the subsequent 18 × information all the time, and in the waiting process of the 60S timer, even if the RTP Media stream sent by the called side is received, the gateway does not process and does not play the local ring back tone, and the gateway executes step 220 again when receiving the subsequent 18 × information.

In this embodiment, the relevant protocol specification and the configuration of the current network relevant network operation are not modified, and only the access gateway level of the fixed-line user in the IMS domain determines whether to play the called side play or the local ring back tone by performing comprehensive judgment processing on the relevant early media, the RTP media stream and the relevant timer of the SIP protocol, and different ring back tones are played to the calling user based on different states of the called user. When a fixed-line user in the IMS domain initiates a call, the situation that the sound reproduction of the fixed-line user in the IMS domain for dialing the non-VOLTE user is kept unchanged, and the normal backward sound reproduction can be heard when the fixed-line user in the IMS domain dials the VOLTE user.

Fig. 8 is a schematic structural diagram of a playback apparatus for dialing a VOLTE user by an IMS fixed-line user according to an embodiment of the present invention. The playback apparatus may be a gateway, and includes an early media parameter determination unit 810 and a playback processing unit 820.

The early media parameter determining unit 810 is configured to determine whether a call request response message returned by the called side carries an early media parameter; namely, whether the 18-letter information returned by the called side carries a P-Early-Media header field or an SDP header field is judged.

The playback processing unit 820 is used for determining the playback processing mode for the calling side according to whether the called side returns the RTP media stream information within the first preset time if the 18-star information returned by the called side carries the early media parameter.

In another embodiment of the present invention, the playback processing unit 820 is configured to play a local ringback tone of the gateway to the calling side if the 180ringing message does not carry the early media header or the SDP header, or the early media parameter in the 183session procedure message is in an inactive state; and if the 183session process message does not carry the early media header field or the SDP header field, the message is not processed, and 18-times information returned by the called side is received again after waiting for the second preset time.

In the above embodiment, the access gateway side of the fixed-line user in the IMS domain determines the playback processing mode on the calling side by referring to the sending condition of the RTP media stream on the called side in the predetermined time and the carrying condition of the early media parameter in the 18-star information, and can solve the playback problem that the calling side cannot hear the ring back tone before the called side picks up the ring back tone when the fixed-line user in the IMS domain dials the non-VOLTE user and dials the ring back tone without the called ring back tone in the same operator on the premise of not modifying the existing SIP protocol playback specification and adapting to the playback processing mechanism of the relevant network element of the current network, and bring better service experience to the client.

Fig. 9 is a schematic structural diagram of a playback apparatus for dialing a VOLTE user by an IMS fixed-line user according to another embodiment of the present invention. The playback device comprises: a memory 910 and a processor 920. Wherein: the memory 910 may be a magnetic disk, flash memory, or any other non-volatile storage medium. The memory 910 is used for storing instructions in the embodiments corresponding to fig. 1 and 2. Coupled to memory 910, processor 920 may be implemented as one or more integrated circuits, such as a microprocessor or microcontroller. The processor 920 is configured to execute instructions stored in a memory.

In one embodiment, as also shown in FIG. 10, the apparatus 1000 includes a memory 1010 and a processor 1020. Processor 1020 is coupled to memory 1010 by a BUS 1030. The device 1000 may also be coupled to an external storage device 1050 via a storage interface 1040 for facilitating retrieval of external data, and may also be coupled to a network or another computer system (not shown) via a network interface 1060, which will not be described in detail herein.

In the embodiment, the data instruction is stored in the memory, and the instruction is processed by the processor, so that the problem that a VOLTE user who dials a non-VOLTE user in an IMS domain can normally hear the ring back tone, and a VOLTE user who dials a VOLTE user who has no called color ring under the same operator can not hear the ring back tone on a calling side before a called off-hook is answered can be solved.

In another embodiment, a computer-readable storage medium has stored thereon computer program instructions which, when executed by a processor, implement the steps of the method in the corresponding embodiment of fig. 1-2. As will be appreciated by one skilled in the art, embodiments of the present disclosure may be provided as a method, apparatus, or computer program product. Accordingly, the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present disclosure may take the form of a computer program product embodied on one or more computer-usable non-transitory storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present disclosure is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

Thus far, the present disclosure has been described in detail. Some details that are well known in the art have not been described in order to avoid obscuring the concepts of the present disclosure. It will be fully apparent to those skilled in the art from the foregoing description how to practice the presently disclosed embodiments.

Although some specific embodiments of the present invention have been described in detail by way of illustration, it should be understood by those skilled in the art that the above illustration is only for the purpose of illustration and is not intended to limit the scope of the invention. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A method for an IP multimedia subsystem IMS fixed telephone user to dial VOLTE user carried by long-term evolution voice includes:

judging whether a call request response message returned by a called side carries early media parameters or not;

if the call request response message returned by the called side carries the early media parameter, determining the playback processing mode of the calling side according to whether the called side returns the real-time transport protocol (RTP) media stream information within the first preset time.

2. The playback method of claim 1, wherein determining the playback processing mode for the calling side according to whether the called side returns the RTP media stream information within the first predetermined time comprises:

if the called side returns RTP media stream information within a first preset time, the called side is transmitted for playing;

if the called side does not return RTP media stream information within the first preset time, playing a local ring back tone of the gateway to the calling side.

3. The playback method of claim 1 or 2, wherein the step of determining whether the call request response message returned by the called side carries the early media parameter comprises the steps of:

and judging whether the call request response message returned by the called side carries an early media header field or a Session Description Protocol (SDP) header field.

4. The playback method of claim 3, wherein the call request response message includes a 180ringing message and a 183session procedure message, the playback method further comprising:

and if the 180ringing message does not carry an early media header field or an SDP header field, or the early media parameter in the 183session process message is in an inactive state, playing a local ring back tone of the gateway to the calling side.

5. The playback method of claim 4, further comprising:

if the 183session process message does not carry the early media header field or the SDP header field, the processing is not performed, and the call request response message returned by the called side is received again after waiting for the second predetermined time.

6. A playback device for dialing VOLTE (voice over LTE) user by IMS (IP multimedia subsystem) fixed-line user comprises:

the early media parameter judging unit is used for judging whether a call request response message returned by the called side carries early media parameters or not;

and the playback processing unit is used for determining a playback processing mode for the calling side according to whether the called side returns real-time transport protocol (RTP) media stream information within first preset time or not if the call request response message returned by the called side carries the early media parameters.

7. The playback apparatus of claim 6,

the playback processing unit is used for transmitting the playback of the called side if the called side returns RTP media stream information within first preset time; if the called side does not return RTP media stream information within the first preset time, playing a local ring back tone of the gateway to the calling side.

8. The playback apparatus of claim 6 or 7,

the early media parameter judging unit is used for judging whether the call request response message returned by the called side carries an early media header field or a session description protocol SDP header field.

9. The playback apparatus of claim 8, wherein the call request response message includes a 180ringing message and a 183session progress message, wherein,

the playback processing unit is configured to play a local ring-back tone of the gateway to the calling side if the 180ringing message does not carry an early media header field or an SDP header field, or the early media parameter in the 183session procedure message is in an inactive state.

10. The playback apparatus of claim 9,

and the playback processing unit is used for not processing if the 183session process message does not carry an early media header field or an SDP header field, and receiving the call request response message returned by the called side again after waiting for a second preset time.

11. A sound playing device for realizing dialing VOLTE user by IMS fixed telephone user includes:

a memory; and

a processor coupled to the memory, the processor configured to execute the playback method of any of claims 1 to 5 that enables an IMS fixed-line user to dial a VOLTE user based on instructions stored in the memory.

12. A computer readable storage medium having stored thereon computer program instructions which, when executed by a processor, implement the steps of any of claims 1 to 5 of a method for enabling an IMS fixed-line user to dial a VOLTE user.