Welcome to Vodafone Community
The Samsung A70 is not showing as an eligible phone model on the lists in the Vodafone page wi-fi-calling.
So if it's not yet working do keep an eye out on that page to see if and when it's been added.
Current Phone > Samsung Note 9 _512Gb > Model: SM-N960 Hybrid-Duos.
Samsung One Ui / Pie.
Samsung Gear s3 Frontier Watch.