The example in Table 1 and Table 2 is the same as the one in Transcode G.711 to G.729A and Convert DTMF Inband Tones to RFC2833 but in addition to the transcoding G.711 to G.729A, SBCs must also be prepared for fax calls that are handled with G.711 on Carrier 1 and using T.38 (Fax Relay) on Carrier 2. Either SBCs, or Carrier 2 may detect the fax tone and initiate a modification of its media stream that agrees with the Fax Tone Treatment setting in the SBC's Codec Entry.
Table 1: Transcode G.711 to G.729A and G711 to T.38 for fax
Configuration | Value | |
|---|---|---|
Carrier 1 Media G.711 w/Fax | Carrier 2 Media G.729A w/Fax | |
PSP | PSP-Carrier1 | PSP-to-Peer |
Silence Factor | 40 | 40 |
Voice Initial Playout Buffer | 10 | 10 |
TOS | 0 | 184 |
Data Initial Playout Buffer | 50 | 50 |
Codec Entry 1 | G711-DEFAULT | G729A-DEFAULT - FaxViaT38 |
Codec Entry 2 | <none> | <none> |
Codec Entry 3 | <none> | <none> |
Codec Entry 4 | <none> | <none> |
AAL Payload Size | 47 | 47 |
T.38 No. Redundant Packets | 1 | 1 |
T.38 Low Speed No. Redundant Packets | 1 | 1 |
T.38 Max Bit Rate | 14.4 | 14.4 |
Data Rate Mgt Type | Type 2 | Type 2 |
Honor Remote Precedence | Disabled | Disabled |
P2P Transcode | Only | Only |
Codecs Allowed This Leg | G.711A, G.711U | G.729, T.38 |
Codecs Allowed Other Leg | (none selected) | (none selected) |
RTCP | Not selected | Not selected |
Silence Insertion Descriptor | Take defaults | Take defaults |
Digit Detect Send Enabled | Not selected | Not selected |
Table 2: Transcode G.711 to G.729A and G.711/T.38 for Fax Codec Entries
Configuration | Value | |
|---|---|---|
| G711-DEFAULT | G729A-DEFAULT FaxViaT38 | |
Audio Encoding | G.711 | G.729A |
Fax Tone Treatment | <none> | Fax Relay |
Packet Size | 10 ms | 10 ms |
Fax Treatment Failure Handling | Continue | Continue |
G.711 Law | Law from other leg | |
Modem Tone Treatment | None | None |
Modem Treatment Failure Handling | Continue | Continue |
DTMF Relay | None | None |
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