Hi, there.
A customer wants to use the R2 E1 protocol and they are facing the issue of voice.
We are trying to capture the packet from the MASG device and found below information.
1. The AG and R2 users are called parties. The softswitch send the ADD command to the A297.
[2019-xx-xx 10:59:10.190] <H.248 MGID:0> MG<-MGC
!/1 [10.xxx.xxx.xxx]:2944 T=369475643{C=${PR=0,A=A297{M{O{MO=IN,RV=OFF,RG=OFF,
tdmc/ec=ON}}},A=${M{O{MO=SR,RV=OFF,RG=OFF},L{v=0
c=IN IP4 $
m=audio $ RTP/AVP 8
a=ptime:20
},R{v=0
c=IN IP4 10.xxx.xxx.xxx
m=audio 54548 RTP/AVP 8
a=ptime:20
}}}}}
2. Then, the softswitch sends the 'Seize' signal to the MASG device (SG{bcas/sz}).
[2019-xx-xx 10:59:10.220<H.248 MGID:0> MG<-MGC
!/1 [10.x.x.x1]:2944 T=372883518{C=1325{PR=0,MF=A297{E=2516603474{bcas/sd,
bcas/casf,r2/r2f},SG{bcas/sz}}}}
3. After receiving the SG{bcas/sz} signal from the softswitch, the AG immediately sends the 'Seize' signaling to the R2 device.
[2019-xx-xx 10:59:10.220] <R2 Port:0/15/6 Ts:9> USER<-AG
Signal Type£º Seize
4. Normally, the R2 device sends a 'Seize' Acknowledge response to the AG. Then, the AG returns a message carrying the 'bcas/sd' signal to the softswitch. The following is an example of the signaling:
[2018-xx-xx 18:54:01.110] <R2 Port:0/18/0 Ts:29> USER->AG
Signal Type： Seize Acknowledge
[2018-xx-xx 18:54:01.110] <H.248 MGID:0> MG->MGC
!/1 [172.x.x.x]:2944 T=215391812{C=1440{N=A829{OE=2684356434{20180913T18540100:bcas/sd}}}}
5. However, the R2 device does not respond to the 'Seize' Acknowledge message. As a result, the AG cannot respond to the softswitch. The softswitch releases the call after three seconds later.
[2019-xx-xx 10:59:13.210] <H.248 MGID:0> MG<-MGC
!/1 [10.x.x.x]:2944 T=372621661{C=1325{PR=0,O-S=A297,O-S=A100001324}}
After analysing the logs, we found that the problem occurs because the R2 device does not respond to the 'Seize' signal of the AG. You need to check the signal on the R2 device. We suggested the customer to check the third party TDM to exchange the configuration.
Thanks.
