Network is currently too busy

Earlier, I have posted a blog on the automated voice from NTC on 'out going facility is not available' (click here to see the post) on May 20. Almost after a month time, I faced another message from it. While trying to call Kathmandu, I used to hear busy tone when the phone I am calling is busy. However, I have never heard of the message 'We are sorry. But the network is currently too busy to handle your call, please try again later'. I assumed that the network traffic was too high at that time and I tried again after 15 minutes. Same message again after 10 minutes. Then I am confused, whether the message is due to network traffic or some technical problem or what?, I have no idea. Anyway, as mentioned earlier, it is more polite message than in the earlier message, 'Out going call facility is not available'.