Hi myassir76,
First of all, either server *can* be Master/Primary. It doesn't really matter which one is Master. If you have two servers, you're kind of agreeing that either one is acceptable to run on. If your second server is not well suited to run production traffic, then you should reconsider your deployment, so that it *can* be Master/Primary at anytime.
Second, You should always have two IP Phone services on your IP Phones:
1) Primary IP Phone Agent (Points to Publisher)
2) Secondary IP Phone Agent (Points to Subscriber)
Then, train your Agents to always press the first button, and if it's not working, press the second button.
Last, the reason why you're experiencing weekly failures on the Publisher node is unknown to us, as you didn't share any logs. I doubt that uploading your logs to the forum will net you a better experience than just opening a TAC case, but if you'd still like to, then go ahead and do it.
I hope that helped explain how things work, or should work for you.