not seeing this issue on build 210 Note: long pressing on 1 will dial voice mail. There is an open bug that if your sim doesn't have voice mail you get no feedback. Perhaps this is what you are seeing and causing the number to disappear.
See bug: https://bugs.launchpad.net/ubuntu/+source/dialer-app/+bug/1338970
not seeing this issue on build 210
Note: long pressing on 1 will dial voice mail. There is an open bug that if your sim doesn't have voice mail you get no feedback. Perhaps this is what you are seeing and causing the number to disappear.
See bug: https:/ /bugs.launchpad .net/ubuntu/ +source/ dialer- app/+bug/ 1338970