Voice Scenario 1
The following ingress and egress policies are used for scenario 1.
| Ingress Policy | Egress Policy | ||
|---|---|---|---|
| allow-codecs | PCMU GSM | allow-codecs | G729 GSM G722 |
| add-codecs-on-egress | PCMU | add-codecs-on-egress | G729 |
| order-codecs | order-codecs | ||
| force-ptime | disabled | force-ptime | disabled |
| packetization-time | packetization-time | ||
Note:
The codec in the ingress policy’s add-codecs-on-egress parameter has no effect in the following examples. Its presence would have an effect if a reINVITE was initiated from egress realm, effectively reversing the roles of the codec policies.-
In the following diagram, PCMU and G729 are offered. Ingress policy removes G729 and allows PCMU. The egress policy adds G729 and strips PCMU from offered SDP and forwards it on to the answerer (ptime is also removed because the last codec was removed).
The SDP answer agreed to use G729 and adds PCMA. The egress policy then strips PCMA from the SDP answer. At this point, the top codec in A1, G729 is checked against O1. Since G729 is not present in O1, it is transcoded to PCMU.
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In the following diagram, GSM is in the original SDP offer. It is then passed through to O1. Egress policy adds G729 and retains ptime from GSM and sends this to the answerer as O2.
The SDP answer agrees to use G729 and GSM, but prioritizes GSM. The egress policy allows both codecs through, unchanged. Because A1 and O1 both have GSM, it is used for the non-transcoded call. Ptime is copied from A0 to the result.
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In the following diagram, G729 in the original SDP offer. Because once G729 is removed, no non-signaling are left in O1, thus the call is rejected.
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In the following diagram, GSM is in the original SDP offer. It is then passed through to O1. Egress policy adds G729 and retains ptime from O1 and sends this to the answerer as O2.
The SDP answer states that the answerer wants to use PCMU. This is a violation of the RFC3264. Therefore the call is rejected.
In this example, when the negotiation fails, the Oracle® Enterprise Session Border Controller sends a 500 message to the offerer and a BYE message to the answerer.
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In the following diagram, GSM is in the original SDP offer. It is then passed through to O1. Egress policy adds G729 and retains ptime from O1 and sends this to the answerer as O2.
The SDP answer replies with G722 G729 GSM and PCMU. PCMU is stripped by policy, G722 is moved to the back of the answer because it was not offered. The top A1 codec was not in O1, and was added by egress policy, therefore the call is transcoded between GSM and G729.
