After-hours phone

F yesterday to make a telephone call, to demand the immediate return to the company, immediately solve a problem, because the version released soon, and this time I was on the subway for half an hour, going to go home at night, and refused, first find out what answer A, find the answer not even lay a few phone can not be found, I can only call a few times over a period of time.
To the home, I asked for a description of the problem, to find people to discuss the issues raised, to find the relevant module responsible discussion, and ultimately to a solution.
But the problem is that this time has been unable to call A. F feedback on the phone, Z old can not get through the phone, not on things these days, while B and C are also often get through. This is why.
Tonight, L reported a problem over, this time I'm home. A module is responsible, could not get through, I have also tried several times to use the phone, or could not get through. Final disposition of.
So indeed there is some problem, the key moment can not find people. In the company of colleagues to work overtime, it is estimated very heart collapse.
Where is the problem?
Management problems: If you need to work overtime or on standby, without informing in advance to the relevant colleagues.
A, B, C own question: could not get through, it may be busy at that time, I would see a return phone call, this should be done.
The two sides need to communicate clearly down in this organization, how to deal with related matters.