For emergencies, any “poor” person can buy a “Tracfone” or something similar. They are frequently on sale for as little as $9.95. There is no monthly fee and there is no fee for 911 calls.
If a “poor” person does get a job and their employer is long winded on the cell phone... they can get a discount if they buy more minutes at a time or buy a more expensive phone or they can pay by the month with no contract. There are a number of competing services, in most cases they are quite competative and actually use the same towers as the major providers. It is the free market in action there is simply no need for a government “subsidy”. It is just a waste.
If there is a cheaper option out there, then by all means the government should be looking at it.
But I get the impression that you would deny the poor even a one-time subsidy of $9.95. Nice. /s