Custom ringtones with FreePBX

[tofuslacks]

We have several T38G's on firmware 38.0.0.130 in the office, all registered to ring the same Ring Group under FreePBX. I'm trying to assign custom (quieter) ringtones to certain phones only and I am running into a few challenges.

1. By setting the "Internal Ringer Text", I am able to get all phones to download a WAV file on a website if I specify a URL, by setting "Alert_Info". However, I cannot get the phone to play the ringtones loaded on the phone itself (both built-in or custom)

2. I would like to get certain phones to call up their own ringtones - another post suggested that Yealink Phones could have a URL pointing to itself:

Alert-Info:<http://127.0.0.1/Vin/MyRing1.wav>;info=RINGTONEID

But this does not seem to work for the T38G. What is the format for links to wav files the localhost on the T38G?