If your calls are not connecting, and in the logs the error "Outbound Call Cannot Complete" is displayed, this usually means there's a problem connecting to the recipient carrier. There are two common reasons:
1) The callerID of the call is being rejected by the recipient carrier, causing the call to fail
If you're transferring a SIP or Phono call, then you likely need to set the callerID to a standard PSTN phone number. This is because Tropo by default passes the callerID of the incoming call to the outbound call destination; with SIP and Phono, the callerID will contain alpha characters and potentially symbols (such as @ or a dash). The carrier networks can, and often do, reject calls with what they consider invalid callerIDs - basically anything other than numbers.
If you're using Tropo.com to call a destination outside of the U.S. and defining non-US caller ID (say you're calling Germany, and setting the callerID for your call to a German phone number) there is a rare chance that the recipient carrier will identify the call as originating from a U.S. datacenter but with a non-U.S. callerID and reject the call as well. Try setting the callerID to +14074441212 as a test - if it passes, that's the cause. We can sometimes help alleviate that issue by escalating to our carriers, so please reach out to support if you encounter this situation.
2) The connection to the recipient carrier cannot be made before the timeout value in the application is hit
This is typically the result of a hard to reach location - we utilize a rotating table of carriers to make our connections, where if one carrier cannot reach the destination, we roll over to the next in the list and so on until we either run out of carriers or the call connects. If the timeout value is short, 30 seconds, 15 seconds, we won't have enough time to try additional carriers to connect the call. Try extending the timeout value and try the call again; if it still fails, reach out to support so we can review the results of the carrier attempts to connect; it may be that the destination is failing to register as available at all, such as a busy signal.