If you can parlay it into an 1/8 wavelength, 25cm is probably not impossible to fit into some monstrously meandered beast that could fit in a phone's footprint. We've come a long way in terms of miniaturizing antennas, though I'm no expert.
But I think your second point hits the nail on the head - cell phones have enough antennas in them, and asking to add another one at such a low frequency is a great way to get your antenna and QA teams to look for a more sane employer, and to put your EMC compliance partner's kids through college :)
But I think your second point hits the nail on the head - cell phones have enough antennas in them, and asking to add another one at such a low frequency is a great way to get your antenna and QA teams to look for a more sane employer, and to put your EMC compliance partner's kids through college :)