I Wireless not that close to T-Mobile
I Wireless isn't that close to T-Mobile, apparently, at least in T-Mobile's minds...
I Wireless bought spectrum from T-Mobile.
The I Wireless ads say "I Wireless, a T-Mobile affiliate"
But my friend that had T-Mobile got terminated for excessive roaming*, for roaming on I Wireless. He now has Verizon instead.
Anyway, I could see this being a useful service. It seems most logical to me, if the 911 dispatches have operator(s) to handle TDD (Terminal Device for the Deaf), to have them handle the texts since both involve getting a textual message and typing a response.
*Most plans in the US have free roaming within the whole US. However, other than Verizon Wireless (who has no roaming limits whatsoever), most cellular providers here have a 50% roaming limit (and for AT&T it's only 40%). That is, if more than 50% of your minutes used per month are roaming for 3 months in a row, your line is cancelled.