There is a small demo lab that one can use for checking DTMF delivery and two-way speech. Also it demonstrates passive (non-intrusive) voice quality analysis based on PVQA.
Feel free to use it in your tests — it is online most of the time. If someone wants to attach a new DID to it, feel free to contact Stanislav Sinyagin (the owner of the service). The lab is running some recent version of FreeSWITCH master branch, and is eventually upgraded. Some video features in the future may also be included.