[asterisk-ss7] signalling ok, but no sound

[Zoltan Markella]

Hi,

I've been trying to get SS7 working with asterisk the last couple of 
days, but had on luck.

My configuration:
- server with a Digium TE420 card, another server with a Digium TE120 
card crossover cable between
- libss7-1.0.2
- dahdi-2.1.0.4
- asterisk-1.6.1.1

The connection between the two servers is working fine. I have set up a 
test pri_cpe/pri_net signalling and was able to do a SIP->DAHDI->SIP call.

/etc/dahdi/system.conf (both machines):
span=1,1,0,ccs,hdb3,crc4
bchan=1-15,17-31
mtp2=16
chocanceller=mg2,1-15,17-31

/etc/asterisk/chan_dahdi.conf (server1)
context=from-ss7
signalling = ss7
ss7type = itu
linkset = 1
pointcode = 20
adjpointcode = 25
defaultdpc = 25
ss7_called_nai=dynamic
ss7_calling_nai=dynamic
networkindicator=international

cicbeginswith = 1
channel = 1-15
cicbeginswith = 17
channel = 17-31
sigchan = 16

/etc/asterisk/chan_dahdi.conf (server2)
pointcode = 25
adjpointcode = 20
defaultdpc = 20
[otherwise same as server1's config]

After starting up both server, SS7 comes up successfully:
MTP2 link up (SLC 0)
--- SS7 Up ---
Resetting CICs 1 to 15
Resetting CICs 17 to 31
Got reset acknowledgement from CIC 1 to 15.
Got reset acknowledgement from CIC 17 to 31.

Here's my call scenario:
SIP/600 (Grandstream phone) -> server 1 -> SS7 -> server 2 -> SIP/555 
(Nokia E71)

Output from server 1:
  == Using SIP RTP CoS mark 5
    -- Executing [1000 at default:1] Dial("SIP/600-08887770", 
"DAHDI/g1/1000,55,tTo") in new stack
    -- Called g1/1000
    -- DAHDI/1-1 is proceeding passing it to SIP/600-08887770
    -- DAHDI/1-1 is ringing
    -- DAHDI/1-1 answered SIP/600-08887770

Output from server 2:
-- Executing [1000 at from-ss7:1] Ringing("DAHDI/1-1", "") in new stack
    -- Accepting call to '1000' on CIC 1
    -- Executing [1000 at from-ss7:2] Dial("DAHDI/1-1", "SIP/555,50,tTo") 
in new stack
  == Using SIP RTP CoS mark 5
    -- Called 555
    -- SIP/555-0890bab0 is ringing
    -- SIP/555-0890bab0 answered DAHDI/1-1

So the call is set up properly. BUT there's no audio on either end!!!
With dahdi_monitor I can see activity on both card's first channel (and 
no other channels, so there's no CIC mismatch), but on server1 I only 
have RX and on server2 I only have TX.

Could anybody give me a hint where my problem could lie?

Cheers,
Zoltan