I found a tiny picture on Google of the sell sheet for this Tetrad Auto-Phonex multi-sport set.
s-l225.jpg
(don't know if that link will work - search "tetrad autophonex sell sheet" & it should be in the images gallery - it's from an old ebay listing, which is no longer active)
Also found a few other signed phonecards: $2 Respert, Reeves & Stoudamire (all hand-numbered to 3000, with the card itself numbered to 4000) & a $5 Joe Smith (hand-numbered to 800, card numbered to 1000 - like your Stackhouse).
Only found one image of a signed baseball $2 pc, but that was hand-numbered to just 100.
I would guess that this product never made it to official distribution. Signature Rookies products are a real mystery - lots of secondary product, from themselves & whomever bought out their stock of cards & memorabilia.