Sony Xperia M was working fine but now is SIM network locked

[Ian_S]

My Sony Xperia M (C1904) was working fine, but now when I power it on, it asks for a "SIM network unlock PIN", and will not recognise my SIM card. What do I do?

Here is what happened:

1. I bought the phone new on eBay, advertised as unlocked. I inserted my old 'Vodafone Australia' SIM card, and the phone worked fine for a year or so.

2. I went overseas, took out my original SIM card and inserted a new 'Solomon Telekom' SIM card bought there overseas. I immediately got the "SIM network unlock PIN" message. I had a spare phone, so put away the locked Xperia M to deal with later.

3. I returned from overseas, took out the foreign SIM card and replaced my old Vodafone Australia SIM card. But I still get the "SIM network unlock PIN" message, even though this is the same SIM card and same network that had originally worked fine.

I have called *#*#7378423#*#*, and gone into the Service Info -> SIM lock menu. The screen info is:

[o] Network Unlimited/255

[x] Network subset 0

[x] Service provider 0

[x] Corporate 0

[x] SIM 0

What do I do now?

[Uliwooly]

@Ian_S

Did you flashed the phone at all? 

[Ian_S]

No, I haven't flashed the phone.

[Uliwooly]

@Ian_S

That's rather odd, you might want to contact the seller or your Local support

[Ian_S · Accepted solution]

A follow-up here to say what happened.

I contacted the support department of my SIM provider. Here's a couple of things that made the case strange.

1. I had forgotten I had not originally purchased an unlocked mobile - the receipt shows it was a 'Vodafone' mobile (i.e. locked to that service provider) - so originally I had no problem.

2. Actually, after coming back from overseas, I mixed up the SIM cards (had two that were red colour, with a Vodafone symbol on them) - pretty silly, but I had re-inserted the foreign SIM instead of the local SIM, hence it was still locked. I actually never tried my local SIM card after coming back from overseas, due to my confusion. I only realised my error much later.

So anyway the local Vodafone support team entered in my mobile's IMEI number to their system and provided me an unlock key, gratis (while I was still erroneously telling them that I had my local SIM card inserted).

Phone now works fine, and I guess the bonus is that it is now unlocked for overseas use too.

Definitely there are shades of Forrest Gump in this tale.