I am using Samsung Galaxy Y GT-S5630 phone with IDEA network provider. I am having signal loss problems many times a times. When I try to make a call, it says "Network unavailable". I though this might be the problem IDEA network, but it was not. I tried checking the same sim card in another mobile and it's working fine, this issue is being observed mostly for every 4-5 minutes. How can I resolve this?
Your phone probably is fixed in 3G mode or is in auto 3G/GSM mode. I suggest you to switch to GSM only mode. That way you won't face a network problem.
Go to Settings > Wireless and Networks > Mobile networks > Network Mode
Select GSM only from that menu.
Also try going to Network Operators from the mobile network menu and try selecting a network manually.