We have a customer with a pair of Iphones that are suffering a weird issue. Zoiper works fine when it is running in foreground, but when Zoiper is in background it unregisters and it is not able to receive calls.
It is weird because we have other customers with Iphones who have not this issue. I am not sure of their IOS version but I am suspecting that there is something in the background parameters (IOS or Zoiper) is not fine.
Clue: if my customer uses Grandstream Wave, it happens the same.
Thank you in advance!