How do I change Viber phone number in a dual-SIM phone from SIM1 to SIM2, when my current Viber account's phone number corresponds to SIM1, but I only have data on SIM2? (e.g. when I have moved to a new network)
(The Viber doc does not say how to)
Android > Wifi & Internet > SIM & network, Enable both SIM1 and SIM2. Set 'default SIM for mobile data' to SIM2.
Settings > Account > Change phone number > New phone number > Continue > Continue (to prompt about spamming your contacts with your new number)
Continue. Viber will attempt to message all your contacts but fail with 'No Service'. Ignore that. (Actually it's desirable to prevent Viber spamming your entire contact book)
Android > Wifi & Internet > SIM & network, disable SIM1. (At this point you could power down and remove SIM1 from SIM tray, if you won't need to reactivate it again/soon).
(None of this procedure is described in
Viber doc > Change phone number but should be. Possibly because dual-SIM phones are not very common in Europe and US.)