Considering what it costs, you might see if the Sonos software would let you exclude the phone (i.e. whitelist or blacklist IPs to send to) - if it's truly broadcasting through the router, you could see if the router could be set to filter those from going to the phone - my current router firmware won't do that, but I'm thinking of going to dd-wrt which should let me pick which packets to allow through.
Thanks for the idea, but it's my understanding that Sonos uses it's own wireless network. I will, however, check their website for a possible solution.
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