A system and method for reducing or eliminating degradation in voice transmission quality resulting from repeated or sequential compression and decompression of voice packets over one or more packet networks. When a voice connection is established between two parties on separate packet networks, the signal is often passed through a PBX and/or over PSTN lines, with the occurrence of two tandem low-bit-rate codecs used to transfer the signal and introducing degradation of voice quality. This situation arises frequently in voice-over-packet applications. The situation can also arise when a call is forwarded from one place to another. The present invention reduces the degradation associated with the transport of voice data and thereby improving the voice quality by removing one of the tandem codecs.
A transmitting/receiving arrangement, gateway and method for transmitting data over packet network, where a cellular network is connected to a packet network and uplink data frames which carry coded data and certain signaling information related to the coding are transmitted from the cellular network towards the packet network, wherein at least all non-redundant information from the uplink data frames is extracted from the frames and transmitted over the packet network. The gateway connects a packet network to a telephony network.
There is disclosed a method of controlling a speech code of speech communications between mobile terminals via an IP network, between mobile switching centers which are interconnected through the IP network. Two mobile switching centers communicate with each other via the IP network using a field in an IP header of a packet, and determines whether coding processes used by two mobile terminals are the same as each other. If the coding processes are the same as each other, then the two mobile switching centers do not convert the coding process for a speech signal, and transmit speech signals from the mobile terminals directly carried on packets through the IP network. If the coding processes are not the same as each other, then the two mobile switching centers convert the coding process for the speech signal into a general-purpose coding process for the speech signal to be transmitted through the IP network.
A method is proposed for reducing the number of vocoders in a wireless network. In certain wireless networks mechanisms exist for bypassing the encoding and decoding of voice traffic at the base station, when both ends of the call are mobile subscribers. This is known as tandem-free operation. A method is proposed where other elements of the network instruct the base station to bypass the vocoding, even when the other end of the link is not a wireless subscriber. These elements could include a packet-switched network used for backhaul, or a terminating node such as a voicemail platform. The network element instructing the base station to bypass its vocoders will then be responsible for transcoding of the voice data. This eliminates the need for extra stages of vocoding.
The invention relates to a method (300, 400, 500) for transmitting information related to tandem free operation, where a cellular network comprising a tandem free operation capable coding-decoding unit is connected to a packet network, an entity, which can be a second network or a terminal, is connected to the packet network and data is transmitted over the packet network between said coding-decoding unit on a first side of the packet network and said entity on a second side of the packet network. The method according to the invention is characterized in that information about the decoding capabilities and tandem free operation capabilities on the first side of the packet network is transmitted (320, 420, 520) over the packet network to the second side of the packet network. The invention relates also to a decoding information exchange arrangement (611), to a gateway (610), to a decoding information transmission arrangement (601) and to a cellular network element (600).
In a digital circuit multiplication equipment (DCME) equipped with tandem pass-through function, a speech coding device and a speech decoding device are resettable in a synchronous resetting mode. The DCME includes a transmission device and a unit to continuously assign and transmit data from a trunk channel to another DCME via a bearer circuit and an exchange during pass-through operation.
