I have configured a SIP account in Zoiper on Android. My phone is a Samsung and I am running Zoiper 2.7.12 with Library revision v2.9.2
When I am entering the account settings, the final step is for the Transport. The app scans the four available transport types and only UDP comes up as being available. I selected this and tapped on Finish to complete setting up the account. After setting up the account, I changed the Account Name at the very top of the list to my company name so I could readily identify the account and then turned on the (purchased) G.729 codec as recommended by my telco provider (MyNetFone in Australia)
On the Accounts screen, I can see that my Company account is active - it has a checkmark next to the name and underneath it, it says Account is ready PUSH
When I go to dial a number, either an external number or an internal extension, after I hit the Call button, at the top of the dialler screen it says Missing Transport Information. After a second or two, the app drops me back at the main screen.
I have gone back into the account settings and verified that UDP is selected under Network Settings > Transport > Transport Type. If I change this to TCP or TLS, the account will not register.
I have also tried deleting the account and adding it back in again and tried uninstalling the app and reinstalling it from the Play Store.