I cannot get signal at all with my new samsung s7

[#1]

I bought a new samsung s7 to replace my old samsung s5. I have been told by the seller that the s7 is unlocked. I have put my old s5 SIM in the s7 but for an unknown reasons I cannot get signal at all. The SIM works perfectly with the s5.

I have been getting the following messages:

1.   When I select search network operators and click 02-UK. The following words appear on the phone: 

      NO SERVICE. Selected network (02- UK) not available. The signal in my area is very good.

2.   When I try to make a call the following words will appear on the phone: PHONE NOT REGISTERED ON NETWORK.

      But the SIM works perfectly with the s5. .

Please I need urgent help. Thank you,

Alex.

[#2]

Hi Alexk04499, it sounds like the phone is actually locked to a different network to me, as it’s saying the 02 network isn’t available!

[#3]

Hi @alexk04499

It sounds like the phone is locked still. 

For example, some people get confused because on the Internet and at car phone warehouse you can buy phones that are unlocked and lock to the first network that they are used on. This is not the same as a fully sim free phone that will always work on any network. 

There's a chance the seller could have reported it stolen to claim on their insurance. Run a free check here which should say it is "clean" rather than stolen on the "blacklist" that blocks phones working on any network when they're reported as stolen.

http://www.imeipro.info/

Your best option may be to go to your local independent phone shop or market trader and they will try every network sim cars until they find which it's locked to and then try to unlock it for a small fee while you wait. 

[#4]

@alexk04499

I agree with others that it sounds as if it is still locked to a network other than O2

[#5]

@alexk04499 I am sorry but it sounds like the shop worker told you wrongly and the phone isn't unlocked.

Sounds like you have done the right thing trying to find the O2 network and because the phone can't sounds locked to another providers network.

[#6]

hi @alexk04499

If the same giffgaff SIM gets signal in another device, then you know the SIM and network are working

The issue lies with the S7

Can you test other known working SIMs in the S7, and can ANY of them get signal bars? If it can't get basic signal with various SIMs, then more likely it is a hardware issue with the phone itself.

I don't think the S7 is locked as suggested above. If this was the case, then the phone would ask for a "SIM network unlock PIN" or similar.

I would take it back to the seller for full refund or exchange.

[#7]

If when you put a giffgaff SIM card in your phone and get an error message and no coverage sign, it's likely that your phone is locked to your previous network.
There are many different ways to unlock your phone, go to giffgaff's Unlockapedia to find out which one works best for you.
http://giffgaff.com/unlock
If your handset is locked to O2 it will work fine with giffgaff.

[#8]

Thank you very much to you all. I have learned a lot from your answers. I will consider everyone of your suggested answers and if I still cannot get it working then I will sent it back to the seller for my money back. Once again BIG THANK YOU.