Asterisk T.38 Gateway testing
Asterisk T.38 Gateway code is now in Asterisk 10
WIKI https://wiki.asterisk.org/wiki/display/AST/T.38+Fax+Gateway
When running a SIP-DAHDI (ISDN) gateway it is mostly sufficient to set the FAXOPT variable in the SIP trunk. The gateway module detects T38 re-INVITES and also detects the fax tone and starts a t38 session. When no activity is detected with ten seconds the gateway module detaches itself from the channel.
[mypeer]
type=peer
host=dynamic
secret=chooseabetterpassword
context=default
setvar=FAXOPT(gateway)=yes,10
Older Asterisk versions need to be patched for t38
Reviewboard
Note: Above patch works with chan_dahdi and chan_iax. If you use other channel drivers and the T.38 reINVITE is rejected by Asterisk with 488 (approx. 4 seconds after the reINVITE was received) then the channel driver need to be changed to return -1 on T38-request indication. Just take a look at the patch how it modified chan_iax.c and apply this similarily to your channel driver.
Note: Most ATAs do not support FEC, but only Redundancy. Some ATAs just ignore FEC, other do not even work at all. Thus, usually it is a good idea to configure Asterisk to use Redundancy instead of FEC (default): add to sip.conf: t38pt_udptl = yes,redundancy,maxdatagram=400
topology 1
ATA1 –SIP+T.38– SS7BOX1 –ss7– SS7BOX2 –SIP+T38– ATA2
call direction ->
ATA1(CALLER) | FIRMWARE | NAT | ASTERISK VERSION BOX1/BOX2 | ATA2/GW(CALLED) | FIRMWARE | NAT | works? | notes |
---|---|---|---|---|---|---|---|---|
Grandstream HT502 | 1.0.1.57 | yes | Asterisk 1.6.2.7/1.6.2.7 | interbell IBG-130 | ? | yes | yes | |
linksys spa 2102 | 5.2.5 | yes | Asterisk 1.6.2.7/1.6.2.7 | interbell IBG-130 | ? | yes | yes | |
Patton SN4524 | 5.5 | yes | Asterisk 1.6.2.7/1.6.2.7 | Grandstream HT502 | 1.0.1.57 | yes | yes | |
linksys spa 3102 | 5.1.10 | no | Asterisk 1.6.2.7/1.6.2.7 | linksys spa 2102 | 5.1.12 | yes | yes |
topology 2
ATA1 –>SIP+T.38– SS7BOX1 –ss7– SS7BOX2 – ReceiveFax/SendFax
outgoing ->, incoming <-
ATA1(CALLER) | FIRMWARE | NAT | ASTERISK VERSION BOX1/BOX2 | spandsp/fax for asterisk | works? | notes |
---|---|---|---|---|---|---|
Grandstream HT502 | 1.0.1.57 | yes | Asterisk 1.6.2.7/ Asterisk 1.6.2.7 | 0.6pre17 | yes | |
linksys spa 2102 | ? | yes | Asterisk 1.6.2.7/ Asterisk 1.6.2.7 | 0.6pre17 | yes | |
linksys spa 3102 | 5.1.10 | no | Asterisk 1.6.2.7/ Asterisk 1.6.2.7 | 0.6pre17 | yes |
topology 3
ATA1 –SIP+T.38– SS7BOX1 –ss7– SS7BOX2 – TDM – analog Fax
outgoing ->, incoming <-
ATA1(CALLER) | FIRMWARE | NAT | ASTERISK VERSION BOX1 | works? | notes |
---|---|---|---|---|---|
Grandstream HT502 | 1.0.1.57 | yes | Asterisk 1.6.2.7 | ? | |
Linksys SPA 2102 | 5.1.12 | yes | Asterisk 1.6.2.7 | yes/no | only one way ata <— tdm |
topology 4
ATA1 –SIP+T.38 – PBX(asterisk) – sip proxy(kamailio)– SS7BOX1 –ss7– SS7BOX2 – SIP+T.38 – ATA2
outgoing ->, incoming <-
ATA1(CALLER) | FIRMWARE | NAT | PBX | SIP PROXY | ASTERISK VERSION BOX1/BOX2 | ATA2 | NAT | works? | notes | |
---|---|---|---|---|---|---|---|---|---|---|
Grandstream HT502 | 1.0.1.57 | yes | Asterisk 1.6.2.7 | kamailio 3.0.2 | Asterisk 1.6.2.7/ Asterisk 1.6.2.7 | linksys | yes | ? |
topology 5
ATA1 –SIP+T.38–Astersk– PRI E1– Carrier–PRI E1– Asterisk –SIP+T38– ATA2
ATA1 –SIP+T.38–Astersk– PRI E1– Carrier — AnalogFax
call direction ->
ATA1(CALLER) | FIRMWARE | NAT | ASTERISK VERSION BOX1/BOX2 | ATA2/GW(CALLED) | FIRMWARE | NAT | works? | notes |
---|---|---|---|---|---|---|---|---|
Grandstream HT502 | 1.0.1.63 | yes | Asterisk 1.6.2.13/1.6.2.13 | Grandstream HT502 | 1.0.1.63 | yes | yes |
In this tipology we have use the patch t38gateway for asterisk 1.6.2.9
N.B. The GrandStream firmware 1.0.1.63 have a new features: “Disable Line Echo Canceller (LEC)”.
This features is “No” by default, and if the echo canceller is active the fax service doesn’t work very well: the fax machine report is ok, but some pages are jumped.
To solve this problem you must disable the Echo Canceller on the Grandstream HT502 putting the feature to Yes