Desperate NFL Teams Still Won't Call Colin Kaepernick

With multiple once-promising NFL teams down to emergency QBs -- from the 49ers to the Bills -- Colin Kaepernick's phone is still not ringing ... TMZ Sports has learned.

The Bills are turning to Nathan Peterman. The 49ers are considering undrafted free agent Nick Mullens. The NY Giants' backup prodigy Kyle Lauletta just got arrested for allegedly almost running over a cop.

And, with Blake Bortles in trouble in Jacksonville, the #2 quarterback for the Jags is Cody Kessler.

There's more ... but you get the point.

Still, sources connected to Kaepernick tell us while journeyman Matt Barkley (8 career TDs, 18 career INTs) got the call from Buffalo, no one has reached out to Colin (72 career TDs, 30 INTs).

When asked why Buffalo didn't kick the tires on Colin, head coach Sean McDermott said, "I know Brandon [Beane] is always looking at all the different options that are available to us, so we’ll leave it at that."

Whatever that means ...

As we previously reported, Kap is still training like a maniac -- working out and throwing every morning at 5 AM with his trainer.

People close to Colin tell us he's staying ready in case that call comes.