In the previous entry we reviewed a few basic concepts we will be using in this and the following entries. For this lab we will leverage the basic Oracle SBC lab, with a minor but powerful modification in the softphone endpoints, these changes are highlighted in yellow in the next image:

With these simple changes applied in both Linphone settings, calls between Alice and Bob will NOT successful:

Let’s make a quick test to confirm and get the call trace for this.

From the ladder diagram above, call was rejected by Bob due to there were NO matching codec to accept the call. This is a common situation that requires transcoding and can be implemented in the Oracle SBC, only if the SBC has the resources required to accomplish this.