One of the new features of 
is the gateway feature. System version 3.2.0.123 (or higher) is recommended. All in this chapter described features and configuration steps refers to system version 3.2.0.123. However, gateway feature also works with version 3.2.0.0. For more info you can also contact support@mayah.com.
1. General
A gateway is defined as a device that performs protocol conversion between different types of networks or applications. A network conversion can be done at all seven layers of the ISO/OSI reference model.
Gateway feature of means that audio received via one communication interface can be rerouted to another communication interface e.g. audio received via ISDN can be IP multicasted in a LAN.
In gateway mode runs two sub codecs. When the connection of the sub codec 1 is framed then the gateway connection on the last sub codec (usually sub codec 2) is established automatically.
Since gateway feature runs two sub codecs it is similar to the backup feature. However, the main difference is that at backup the last sub codec is active when the first sub codec is not(!) framed whereas at gateway feature the last sub codec is active when the first sub codec is framed.
Audio received via ISDN is IP-multicasted in a LAN
In the diagram above audio is received via ISDN with quality of MPEG L2, 32 kHz, 128 kbps, joint stereo. This audio is IP-multicasted to the LAN in the quality AAC (MPEG2), 48 kHz, 128 kbps, stereo.
2. Parameters to set
For Gateway mode two kind of parameters must be set:
2.1 Gateway connection
The gateway connection is the connection to which the audio received by sub codec 1 is routed to.
It can be:
| • | The last connection |
or
| • | A phone book entry (recommended) |
2.2 Audio interfaces
The audio is internally routed via the audio interfaces. Therefore the audio output of sub codec 1 must be identical to the audio input of the gateway sub codec (usually sub codec 2) i.e. in case of gateway mode uses a phone book entry the audio type of the encoder profile of this phone book entry must be the same as the audio output of sub codec 1. Therefore very often the following configuration is used:
| • | Audio output of sub codec 1: adat12 |
| • | Audio type of encoder profile of gateway phone book entry: adat12 |
When audio should also be routed back then the audio input of sub codec 1 must correspond to the audio type of decoder profile of the gateway phone book entry.
Note:
The audio is routed in an non-decoded state i.e. even in gateway mode sub codec 1 first decodes the audio before it routes it to the gateway sub codec (usually sub codec 2). This means that even in gateway mode no trans coding is used and therefore every gateway audio routing means one more coding generation.
3. Restrictions
Theoretically any kind of transmission can be routed to any other kind of transmission. However, there are a few restrictions:
| • | If the gateway sub codec uses IP then IP/RTP must be used |
| • | X.21/V.35 connections cannot be routed to another X.21/V.35 connection |
| • | Gateway mode cannot be used if backup mode, dual codec mode or point to multipoint (PMP) is active |
4. Considerations
In the following considerations it assumed that the gateway sub codec is sub codec 2 (which is the case for CENTAURI II 300x; CENTAURI II 330x, MERKII and GANYMED 1102).
4.1 Last ISDN B-channels
Since there is no special parameter to determine which B-channels are assigned to sub codec 1 (main line) and sub codec 2 (gateway line) in gateway mode the last available B-channels are automatically assigned to sub codec 2. This means:
| • | At ISDN gateway phone book entries the last ISDN numbers must be used e.g. with a CIM40 ISDN card and a bit rate of 128 kbps the numbers must be assigned to #8 and #7. |
| • | At a gateway scenario using ISDN for sub codec 2 the ISDN cables must be connected to the last S0 ports e.g. at a CIM40 ISDN card and a bit rate of 128 kbps the ISDN cable must be connected to S04. |
4.2 Different IP ports at the sub codecs
At RTP different sub codecs use different RTP ports (see also chapter Necessary settings for framed connections/How to establish IP connections/IP Ports). This means that e.g. sub codec 2 uses port 5014 and 5015 by default (provided system software version >= 3.2.0.30).
However, when the gateway connection should be established to sub codec 1 of another Mayah codec then ports 5004 and 5005 must be used. Therefore at the gateway phone book entry the IP address must be look like this:
<IP-address of other side codec>:5004
e.g. 88.217.252.72:5004
5. Useful hints
5.1 Independent testing of main line and gateway line
It is strongly recommended to test independently the main line connection and the gateway line connection i.e. test of both connections with inactive gateway mode. However, the notes of item 3 and 4 should be considered.
5.2 No ancillary data transfer
By default the ancillary data is not routed together with audio.
6. Configuration
The gateway mode can be configured via menu item Settings/Others.
7. Looking of Remote main window
When gateway mode is active the selected sub codec is also displayed in the main window. It can be switched between the sub codecs with the short cut key combinations <STRG><1> (sub codec 1) and <STRG><2> (sub codec 2).
