I let clients text me, and take text bookings - I know I'm one of the few but it's mostly because my day job means i can't always talk on the phone and it's just easier for me.
If a client I've met before texts me a hi or whatever I'll answer to be polite...generally they are just 'checking in' anyway and they rarely get into long conversations. When they do, or if it's someone I've never met and they're going on too much, I generally end it with 'Please give me a call or text when you'd like to make a booking. Thanks, my name xx'. If they are legit, they get the message and leave it like that. If they go on further, I write them off as timewasters and don't respond any further.