As promised I noticed in an earlier referenced Blog Post that I never did publish the VOIP SIP settings that allow us to use a standard Physical SIP voice over internet telephone on the Swisscom network.
So I just wrote up our working settings here
https://majzel.blogspot.com/2014/10/voip-phone-settings-for-swiss-phone.html
AFAIK the Swisscom IP telephones that are for sale are not compatible with standard SIP protocol phones, in other words you can't buy a Swisscom IP phone and use it in the same way as say our Gigaset C610 IP phone.
Note: If I am wrong about the Swisscom IP phone compatibility then please can somebody publish a working SIP configuration in suitably clear terms.
We have been blissfully happy with our Gigaset phone and also the 2 different SIP subscriptions that allow us on the same Gigaset phone to have
a) a Swiss telephone number
b) a UK London telephone number
As per other Support Community post, our Gigaset C610 has developed a small fault and so I was seeking suggestions for a replacement SIP phone. I'm still waiting. Meanwhile I can recommend the Gigaset C610 IP.
Regards Marcus Bennett.