Edit: I did do a search and found nothing, but now I've posted I see that this question has come up before although the answer is to do what I'm doing ie add 'in the sitting room' or 'from TuneIn' to the command, which isn't a really great solution.

You can get bbc stations to play through sonos speakers.  You need to download IFTTT to your phone. Then link your sonos and alexa to IFTTT . If you then go to the Sonos app and add radioplayer you can find the BBC radio stations from there and add them to my sonos.  Then  go to IFTTT tap get more and the + button. Tap THIS , Type in Amazon alexa. Tap "Say a specific phrase" type in your trigger phrase in the box that says what phrase. Then follow the boxes that come up. 

SOLVED - Thank you Derek123.   The IFTTT route works well and results in simpler commands as you can also pre-specify the destination Sonos speaker in the set-up. So simply ‘Alexa, trigger Radio Four’ connects directly to the kitchen speaker.  I have been trying to find a flexible solution for some time and the end result is exactly what is needed and I can forget about messing around with Google Home etc

My pleasure.  So glad it worked for you. 

Thank you Derrick123, now works as it should again. Took an hour to configure but got there in the end. A couple of additions which should help. I had no '+ button' but scrolled down to 'create your own' (for some reason searching for this doesn't work). When you are looking for an 'action' in the menu, search for Sonos, and click on 'play favourite', you then get to the menu you need. Sounds complicated, it is a bit but once done it makes sense!

Thanks Derrick. I have been demanding Radio 4 in vain for ages. Alexa would give me random rural radio stations and podcasts or tell me she could not find a station with that name! I will have to explore the possibilities of IFTTT further. 

I came back to this to see if anyone had a solution and to my delight someone does. So another thanks to Derrick123 as this works for me although my wife says she refuses to use the word Trigger.…

And as someone else mentioned above, when selecting SONOS select Favourites to select BBC Radio 2 from Realplayer.

Bizarrely I still have TunedIn Radio 2 in my favourites and it still played… but I changed it to RealPlayer.

I also didn’t like to use Trigger to get the BBC radio station to play so I worked out that I can use the IFTTT set up to create a routine within the Alexa app. I have created a routine that activates with’Alexa play Radio 2’ which runs the IFTTT routine to run BBC Radio 2 from Realplayer. The IFTTT routine shows as an option under Action when setting up the Alexa Routine and then from within that you can select any routine that you have created within IFTTT.

Having the same problem - if you have an Amazon Echo paired with an old Sonos Play 1 (using the echo to supply voice commands to the Sonos) then there’s no easy way to get it to play BBC stations via voice commands. Non-bbc work via TuneIn and it reroutes the audio to the Sonos properly. For BBC you have to say “Alexa listen to Radio 6 Music from BBC” which is cumbersome in itself, but also doesn’t respect the grouping that says you want it to play on Sonos rather than Echo. 

Whilst I could set up an individual voice command per speaker it would be nice - as with literally all other non-BBC radio stations - to have one command that works on all my devices whether they’re Alexa-enabled Sonos Ones or a pairing of Amazon Echo and Play 1. 

Please see my consolidated instructions to resolve this: https://en.community.sonos.com/amazon-alexa-and-sonos-229102/step-by-step-guide-to-play-bbc-radio-station-via-voice-control-6834993

Thank you UKMedia - I appreciate your help, though I will point out that even this way requires having a separate command per room which isn’t very “Alexa”. I just want things back the old way, the same command whether BBC or not, and playing on the speaker I’m stood in front of (or paired with) rather than having to call it out by name. I don’t think we have a solution for that yet. 

It is possible to output to either a Specific room, an existing Sonos Group or all Rooms but I agree that this still doesn’t reflect the old functionality before the BBC pulled support for TuneIn via Voice.

Now it seems to work without having to specify the room, if you ask for “Radio ox] from BBC” and your groups are set up correctly 

Without “from BBC”… just plays on the Echo 

I had this working consistently for months. I have an Echo Dot and a Sonos speaker set in each Alexa Group with the Sonos speaker set as the Preferred Speaker. If I said “Ask BBC to play Radio 4” it would play on the preferred Sonos speaker(s) for that Dot. 
 

For no obvious reason this has stopped working in the last few days and now the BBC skill always plays on the Echo Dot. I now have to use the Sonos app to play Radio 4 through the Sonos speakers. I have 3 Alexa Groups set up like this and it is affecting all of them.

If I ask Alexa to play music (i.e. not using the BBC Skill) without specifying a room, it still plays on the Preferred Sonos speaker so it doesn’t appear to be a problem with the Alexa set-up. I can only assume it’s a problem with the BBC Skill. 
 

Has anyone else experienced anything similar in the last few days?

I suggest that you disable then enable the BBC skill in the Alexa App. If 5he problem persists, then please disable then enable the Sonos skill and retest.

I have the same problem as of a similar timeframe.  There are a few possibilities, including it being one of those strange temporary glitches that seem to affect Alexa on a particular system from time to time.  If it were a general problem I would have expected more posts on it by now.

I have tried most things I can think of.  It is not convenient for me to do a complete system reboot just for this issue at the moment.  I will try it at some point, but with little optimism that it will help.

I have tried disabling and re-enabling the BBC skill and the Sonos skill.  I have deleted the whole Alexa group and set it up again.  The preferred speaker is respected for Amazon Music and the non-BBC radio stations I have tried.

I can’t help wondering if this still goes back to the issue of the BBC removing BBC stations from TuneIn, which means that play on Sonos relies on the BBC skill.  Up to now, that respected the preferred speaker provided I used the right form of words.  Now all instructions to play BBC stations are played on my Echo Dot instead of my Sonos speaker.

I have three groups set up with preferred Sonos speakers and all are suffering from this problem.

So my experience matches that of @Simon_6.

I’ll give it a couple of days to sort itself out before I spend any more time on this.

It looks like the trick of adding “…. from the BBC” to the Alexa command to a Dot for asking for a BBC radio station to be played on a Sonos Device in the same room has been disabled - temporarily or permanently. 

If anyone does work out a way to do this again, please post - I don’t want to have to replace my Connect with the new Alexa enabled version (first world pains I know)