On 05/30/2018 04:20 PM, Avi Marcus wrote:
Beware that "low cost provider" may not just reject the call, which you can recover from, but can mess you up in a large number of ways. Some of which you can try to work around (debugging + time), some of which you may not be able to figure out.
  • Not properly passing along DTMF
  • very long PDD
  • FAS fake answers
  • Returning "USER_BUSY" when it's not actually busy
  • Returning "NORMAL_TEMPORARY_FAILURE" when it's actually busy
  • poor audio quality
  • Issues with proxies/re-invite/switching codecs, etc.
  • .. and I'm sure many more.
... Just some of the many issues I've run into when using multiple carriers and terminating to countries around the world.

Thank you very much.
µPC