BEARER_CAPABILITY (l=3) 90 90 a3

[genyfox]

Hello,
when call income from public as below (BEARER_CAPABILITY (l=3) 90 90 a3), and if internal user set immedated forward to external number, then call is not forwarded..
is it public problem? or can I config OXE to handle this call?
when call incom 'BEARER_CAPABILITY (l=3) 80 90 a3' then user fowarding is working normally.

(forward not working)
______________________________________________________________________________
| (608400:000151) Concatenated-Physical-Event :
| long: 55 desti: 0 source: 0 cryst: 2 cpl: 9 us: 0 term: 1 type a5
| tei: 0 >>>> message received : SETUP [05] Call ref : 03 f5
| SENDING COMPLETE
|______________________________________________________________________________
|
| IE:[04] BEARER_CAPABILITY (l=3) 90 90 a3
| IE:[18] CHANNEL (l=3) a9 83 8d -> T2 : B channel 13 exclusive
| IE:[1e] PROGRESS_ID (l=2) 80 88
| IE:[6c] CALLING_NUMBER (l=13) -> 21 83 Num : 01089758048
| IE:[70] CALLED_NUMBER (l=5) -> a1 Num : 2012
|______________________________________________________________________________


(foward work normal)
______________________________________________________________________________
| (602616:000009) Concatenated-Physical-Event :
| long: 55 desti: 0 source: 0 cryst: 2 cpl: 11 us: 0 term: 0 type a5
| tei: 0 >>>> message received : SETUP [05] Call ref : 04 07
| SENDING COMPLETE
|______________________________________________________________________________
|
| IE:[04] BEARER_CAPABILITY (l=3) 80 90 a3
| IE:[18] CHANNEL (l=3) a9 83 9f -> T2 : B channel 31 exclusive
| IE:[1e] PROGRESS_ID (l=2) 80 88
| IE:[6c] CALLING_NUMBER (l=13) -> 21 83 Num : 01089758048
| IE:[70] CALLED_NUMBER (l=5) -> a1 Num : 9799
|______________________________________________________________________________

[genyfox]

I saw other posts said to add 'Fax' on ARS Route - Qulity. Normally I just add 'Speech'.
After adding 'Fax' it works normally. Could anyone explain why?
I found that 80 is "speech" and 90 is "3k1 audio" but cannot understand clearly.
Thanks.