Transcoding

Service providers have traditionally relied on TDM interconnections to move voice traffic on and off their networks, in part because of the high quality and reliable interconnections inherent in the technology. Advances in VoIP-based technology present a new lower-cost alternative that offers quality and reliability that rivals TDM networks. IP to IP transcoding from carrier to carrier is now becoming a more common practice. The combination of the increased security, quality/reliability, advanced features, and the lower cost of VoIP is encouraging service providers to use VoIP peering solutions for network interconnection.

The use of the Public Internet brings up questions of security, quality, media interworking, and trust. Session border controllers and media gateways are the edge devices ideally suited to address these new challenges. The IMG solves one of these challenges by offering media interworking or more commonly referred to as IP-IP Transcoding. The transcoding capabilities of the IMG 1010 enable solution developers to connect to a broad range of different networks and convert among various audio formats.

 

IMG Solution

The IMG solves current and future problems in next generation networks with its integrated transcoding. The IMG supports IP to IP Transcoding in both SIP and H.323 and also supports IP hairpins. The ability to support IP hairpins enables not only IP signaling translation, but media translation as well. As VoIP networks evolve and move away from the PSTN, wide-band codecs will gain popularity. The IMG, coupled with a Session Border Controller, is the ideal solution to bridge islands of VoIP traffic. See information below which displays the transcoding capabilities of the IMG 1010 and IMG 1004.

 

 

 

dg_transcoding_dialogic_logos.png

 

 

 

Codecs/Maximum IP Transcoding Sessions

The next two tables display the number of transcoding sessions per profile that is supported on the IMG 1010 and/or IMG 1004. Note that a Transcoding session uses two IP ports. One port for incoming and second port for outgoing. The table below displays number of sessions supported per Profile (Not Port Density). For a breakdown of IP Port Density supported per profile and codec please see the Vocoder Information topic.

 

Note: The individual profiles (Profile 5, Profile 6, etc) are configured on the IMG by setting either the parameter Host_1010_Flag on the IMG 1010 or the Host_1004_Flag on the IMG 1004. These parameters are located in the dhcpd.conf file in /etc. See Setting Host Flags link for more information on configuring IMG for a specific profile.

 

Max Transcoding Sessions supported per Profile on IMG 1004:

Supported Codecs

Profile 5

SRTP Off

Profile 5

SRTP On

Profile 6

SRTP Off

Profile 6

SRTP On

Profile 7

SRTP Off

Profile 7

SRTP On

Profile 8

SRTP Off

Profile 8

SRTP On

G.711 a-law

64

42

42

36

42

36

60

42

G.711 u-law

64

42

42

36

42

36

60

42

G.723.1 5.3kbps

64

42

42

36

42

36

60

42

G.723.1 6.3kbps

64

42

42

36

42

36

60

42

G.726-32/G.721

64

42

42

36

42

36

60

42

G.729 a/b/e

64

(G.729e=*N/S)

42

(G.729e=*N/S)

42

36

42

36

60

(G.729e=*N/S)

42

(G.729e=*N/S)

iLBC

*N/S

*N/S

42

36

42

36

*N/S

*N/S

GSM-AMR

*N/S

*N/S

*N/S

*N/S

42

36

60

42

GSM-FR

*N/S

*N/S

42

36

42

36

60

42

EVRC

*N/S

*N/S

*N/S

*N/S

42

36

*N/S

*N/S

Clear Channel

64

42

42

36

42

36

60

42

*N/S = Not Supported

 

Note: The numbers displayed in the table below is for an IMG 1010 with one VoIP module installed. If the IMG 1010 has only two VoIP Module installed then the numbers displayed below will be doubled.

Max Transcoding Sessions supported per Profile on IMG 1010:

Supported Codecs

Profile 5

SRTP Off

Profile 5

SRTP On

Profile 6

SRTP Off

Profile 6

SRTP On

Profile 7

SRTP Off

Profile 7

SRTP On

Profile 8

SRTP Off

Profile 8

SRTP On

G.711 a-law

256

168

168

144

168

144

240

168

G.711 u-law

256

168

168

144

168

144

240

168

G.723.1 5.3kbps

256

168

168

144

168

144

240

168

G.723.1 6.3kbps

256

168

168

144

168

144

240

168

G.726-32/G.721

256

168

168

144

168

144

240

168

G.729 a/b/e

256

(G.729e=*N/S)

168

(G.729e=*N/S)

168

144

168

144

240

(G.729e=*N/S)

168

(G.729e=*N/S)

iLBC

*N/S

*N/S

168

144

168

144

*N/S

*N/S

GSM-AMR

*N/S

*N/S

*N/S

*N/S

168

144

240

168

GSM-FR

*N/S

*N/S

168

144

168

144

240

168

EVRC

N/S

*N/S

*N/S

*N/S

168

144

*N/S

*N/S

Clear Channel

256

168

168

144

168

144

240

168

*N/S = Not Supported

 

 

Media / IP Transcoding Supported

The table below displays the transcoding ability of the IMG as long as the appropriate licensing and profiles are loaded.

 

G.711

G.723.1

G.729 A/B/E

AMR

iLBC

G.726

GSM-FR

Clear Channel

G.711

 

x

x

x

x

x

x

x

G.723.1

x

 

x

x

x

x

x

x

G.729 A/B/E

x

x

 

x

x

x

x

x

AMR

x

x

x

 

x

x

x

x

iLBC

x

x

x

x

 

x

x

x

G.726

x

x

x

x

x

 

x

x

GSM-FR

x

x

x

x

x

x

 

x

Clear Channel

x

x

x

x

x

x

x