The most popular Ding Xin transcoding gateway conn

SIP (Session Initiation Protocol) is a text-based application layer control protocol, which can be supported and applied to multimedia services such as voice, video and data, as well as special services such as presence and instant message. In the era of rapid development of Internet, VoIP technology has been further developed, and sip based voice, video and other applications are more and more widely. The core IMS of operators is one of them. Now major operators are opening more and more IMS voice dedicated lines directly to enterprise users

it is well known that the biggest feature of SIP protocol is flexibility, openness and easy expansion, but it is also because of these points that some details are not so rigid. The IMS core carries many services, so various fields are customized on the SIP protocol to meet the needs of business applications, especially the volt voice service. The rules for operators in different regions to play ring back tones may be different, Friends who have connected to IMS voice dedicated line may encounter this phenomenon: during the operation of IPCC (call center), some called numbers are directly connected without ringing tone prompt during the external call of the seat, or they call some shutdown, shutdown and rejection numbers, and the seat cannot hear any prompt tone at all

Dingxin Tongda transcoding customs has rich docking experience with IMS lines of various operators across the country, and has also learned relevant rules from relevant operators. Dingxin transcoding customs can be perfectly compatible with IMS call process and provide users with the best solution. The groups are as follows:

I. mobile volte playback rules:

whether the playback of volte user calls is consistent with the 3G ring back tone base check indicator, so as to ensure the unity of customer experience and perception.

for calls in the volte domain, the basic ring back paper price increases little? The tone is played by the calling side volt12 and a set of TestStar professional computer control software based on the windows operating system, so as to reduce the network load. In the asrvcc scenario, the terminal switches from LTE to 2G in the ringing state, and the ringing tone is still played by the calling terminal; The generation of basic ring back tone shall comply with the provisions of f.2.5 in 3GPP TS 22.001

if the calling terminal does not carry the p-early-media header field in the received 18x message or carries the header field but the value is inactive, the terminal should start local playback, and the specific playback method should follow the provisions of f.2.5 in 3GPP TS 22.001

the basic ring back tone is put through the 18x message in the normal call process or the abnormal process. The IMS network may have multiple 18x messages in the call. The value carried by the PEM (p-early-media) in the message is sendrecv/sendonly/gated/inactive, which is the index e for comparing the soft and hard of various materials; The calling user needs to adapt whether to transmit the RBT transparently and play the local ring back tone according to the field value of the p-early-media header

media negotiation has been completed, and the subsequent media playback notification should be realized through update

when the called volte user is covered by 2/3g, for call waiting, call holding, called busy and call rejection playback, it should be played by the volte as where the service triggers, and carry the p-early-media instruction in the message of playing RBT

avoid secondary playback. After playback, send 487 message to release resources. 487 should carry the corresponding reason value of q.850

II. Dingxin transcoding off the ring back tone processing rules

according to rich docking experience, Dingxin transcoding off has done a compatible processing for IMS playback rules, which perfectly solves the problem that calls cannot hear the ring back tone. In order to be compatible with different group applications, transcoding off has made the ring back tone configuration item. If SIP trunk is connected to the operator's line, select the IP side transparent transmission mode

if the IMS line is registered, select the adaptive mode, and the transcoding off will automatically determine whether to transmit the ring tone through or play the local ring back according to the content carried by the received 18x message or update message, which is handled intelligently