voice quality is poor in simultaneous calls

[pavan.kumar]

Hi,

I'm using cisco 1601R router .

The show version details are given below :

Cisco Internetwork Operating System Software

IOS (tm) 1600 Software (C1600-Y-M), Version 12.0(7)T, RELEASE SOFTWARE (fc2)

I'm having an ISDN line through which i want to make 6 simultaneous voip calls.The voip CPE i'm using is CISCO ATA186 with 2.16.2 version.

I dont have any voip quality problem when i was doing 3 simultaneous calls, and when i start doing 4th voip call its OK, not like earlier, but as soon as i do 5th ,the voice quality is becoming very poor. Voip calls are on the basis of H.323 and voice codec we are using is G.723ar63 . And the known factor is ISDN supports 128Kbps . And when i see sh isdn bri 0 ,showing only 80 to 90 Kbps of utilization.

When i see show processes cpu after the first call placed it is going upto 40% later for the 2nd

3rd , its becoming normal and showing only 20%.

I tried with another Zyxel100IH prestige ISDN router the same scenario.but the same result.

please help me out.

[generalee]

Try G.711. You can make this change in the regions of CCM. I have used this with success with analog fax machines and phones.

[pavan.kumar]

G.711 consumes more bandwidth than G.723 if i'm not wrong . below is my network topology

3ATAs----D-LinkSwitch----1601R ISDN-----GATEWAY----

VOICEGATEWAY.

I connected 3ATAs to ISDN and making calls .

Please clarify

[spremkumar]

Hi

as u said 711 will consume more B/W ,y dont u try with G.729..i hv attached a sample comparsion sheet here..

Standard Packet Duration Data PPS

Size RateBits Simplex

G.711 120 15ms 64K 66

G.729A 10 10ms 8K 100

G.723.1 24 30ms 5.3/6.4K 33

do chek this link ,there r several scenarios discussed hope one of tht with bri will help u out.

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configuration_guide_chapter09186a0080080aa3.html

regds

prem

[pavan.kumar]

Hi,

G.729 supports only one FXS port in ATA186. I cant make two simultaneous calls with G.729 codec using ATA. I'm using G.723ar63 codec ,with this i can make two simultaneous calls .So i think G.729 is not the required codec which one to use to my problem .

If you know any solution to configure the cisco ATA for two simultaneous calls with G.729 ,please send me the configuration ,where i need to modify in ATA.

Regds

Pavan.M