Ummm.
The first two paragraphs of your link:
What to do if you need urgent police help through the 999 service, but can’t speak.
If you’re in an emergency situation and need police help, but can’t speak, Make Yourself Heard and let the 999 operator know your call is genuine.
That's just gibberish.
The rest does look too complex. Making the 55 response on 999 available sooner looks more sensible to me. Also including it on landline and pseudo-landline (PSTN replacement). Adding 888 isn't necessary.
The 55 also needs to reveal location if available.
An interesting article re 999 answering times. Though that refers to the police response, which presumably comes after the call handler transfers it to the requested service. AIUI that initial response can be longer.
Connections: OnePlus 8 Pro on Three 4+ (LTE)/5G and at home Three Mobile, with (Three)ZTE MF286D router giving about 113/20Mbps.
The best of all possible worlds?