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Yitzakh Stine
Beginner

2-way Audio Issue with G722.2 Codec, 3PCC

I'm using an IP-DECT phone and an 8861-3PCC Cisco Phone on Cisco BSFT network. 

My issue is with 2-way audio when using G722.2 codec. (Calls are successful with PCMU & G729) When IP-DECT user dials Cisco device, 2-way audio is clear, signaling is normal & as expected. However, when 8861 device dials IP-DECT user, Cisco device cannot hear anything IP-DECT user is saying. DECT user can hear what Cisco device says, just not vice-versa.

I checked all SDP packets and noticed a difference in the dynamic payload type used for G722.2 depending on who initiates call. 
When DECT initiates call, 110 payload type is used (AMR-WB; octet-align=1). When Cisco device initiates, he offers 96 & 103 payload types for G722.2, 96 is used (AMR-WB, octet-align=0).

My question is multi-faceted since I'm also trying to learn: Why is there an audio issue since signaling seems to be accepted and processed successfully? Why the difference in payload types for same codec? I've spent a small, yet fair amount of time in the SIP/VoIP world, but still learning so any assistance is nice!

1 ACCEPTED SOLUTION

Accepted Solutions
Yitzakh Stine
Beginner

I believe found the issue.
DECT user only supports octet-align=1
Cisco device can support 0 or 1 for incoming calls but sends only 0 by default when initiating call. Because of this mismatch, unless transcoding is used, there will be error. 

https://docs.oracle.com/cd/F12246_01/html/sbc_scz830_acliconfiguration/GUID-497DA706-2359-4D7E-9876-F2CA5A32747C.htm

View solution in original post

2 REPLIES 2
bijpraka
Cisco Employee

What is the firmware version on the 8861?
Yitzakh Stine
Beginner

I believe found the issue.
DECT user only supports octet-align=1
Cisco device can support 0 or 1 for incoming calls but sends only 0 by default when initiating call. Because of this mismatch, unless transcoding is used, there will be error. 

https://docs.oracle.com/cd/F12246_01/html/sbc_scz830_acliconfiguration/GUID-497DA706-2359-4D7E-9876-F2CA5A32747C.htm

View solution in original post

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