K800i Will Not Switch on

Hi I'm a mobile phone Tech.

If your mobile phone is on a contract with a service provider, most of the times it will be locked in with them for the duration of the contract,
So if you try to insert a sim card from a different service provider, it may say "sim card not valid'
Try to insert your original sim card and see if that works.

Otherwise if this IS your original sim card and all of a sudden this message "sim card not valid" has appeared, then the sim card has gone faulty and you need to get a new sim card from your service provider eg... Vodafone.

Hope this is helpful
MobileJB

you need top unlock it while use it for other network , try unlcok codes , if you want to unlcok means try here http://www.wickedunlock.com/

you can get your PUK only by phone The Vodafone costumer care. use another phone or an other sim card to make a call.

it turned out to be the sim card. I went to my nearest vodafone shop and got given a new sim card

Sir,
You are suggested to visit the near by connection service center of your mobile such as Vodafone, O2 or Tmobile usually have the code to unlock the phone this may also take some money almost 12 $

press *#06# on your keypad.

A 15 digit code will appear on the screen.

This is your IMEI: number.

It should consist of 15 digits.

Send it to me.

I will reply with the unlocking code that you need.

Hughie.

Your sim card might be loose in it's place. Or you may need to "open line" your phone.
Better solution? Purchase a new sim,not a vodafone sim. For you to know what the problem is.
A rate from you for this solution according to the benefits obtained will be much appreciated. tnx! Further questions? don't hesitate to post......good day!

Hi how do i get my sciphone to accept my 3mobile sim card when i put it in with my tmobile sim it will only recognise tmobile my 3 mobile is a contract sim can that be the problem
cheers willie

Dear Sir/Madam,

To unlock the phone u call the customer service of vodaphone and ask the CODE to unlock the phone.

Step 1: Getting the mysterious unlock code
Persuading your phone network carrier to give you the unlock code to your cell phone may be the most difficult part of the entire process.
The code is a number entered into U.S. phones to allow a SIM card from a third-party carrier to work with your cell phone. Internet message boards are full of complaints about carriers withholding codes along with offers of software or services for unlocking. But I also found a number of postings from people who said they got the code from their carrier simply by asking.
I called AT&T as a customer and explained my situation: I was going to the U.K. for one week, and would like to avoid high roaming fees by using a local SIM card. I explained that I had no wish to permanently change carriers, as I had a two-year contract and was happy with their service. Could I please have the unlock code for my phone?
I was met with a little reluctance. The first customer service representative told me this would require her to "submit a case" for getting the unlock code and that once approved it could take up to a week for the "unlock code team" to figure out the code for my particular phone. Her supervisor then tried to sell me an international plan that would reduce the usual $1.29 per-minute charge to "only" 99 cents per minute. I promptly declined. He then told me that it could take a week to get the code because it must be sent from the manufacturer.


Step 2: Unlocking your phone, activating the SIM card
I chose Vodafone as my test case and went to its store in Paddington Station upon arriving in London. Gabriel, the Vodafone employee who helped me, was kind enough to let me verify that the unlock code and the Vodafone SIM card worked before he charged me for the SIM card.

Before doing anything, I confirmed my phone's IMEI by typing in "*#06#" and "send". AT&T had sent the unlock code for the correct IMEI.
Next, I removed my old SIM card, inserted the new prepaid Vodafone SIM card and turned on my phone. I was immediately prompted to enter my eight-digit unlock code and instructed to press "OK". Doing this made the SIM and my phone available for use.
Vodafone's activation process was simple. You activate, get your phone number, set up voice mail, check your balance and add to your balance by punching in a numeric code for each function and pressing send. The company gives you a little book and cheat sheet to remember the codes.
The SIM card kit, which costs $10 (5 pounds) and includes $2 worth of talk time and free weekend calls and texts, remains active as long as you use it at least once every nine months. This means you can reuse the same SIM card and phone number the next time you travel where that network is available.
There are several price plans to choose from, depending on variables like mobile TV, free nights and weekends, video or picture messaging, video calling, mobile broadband, unlimited monthly usage and texting. I went with the standard "Anytime" plan that was 60 cents for the first three minutes of the day and 20 cents after that. You could save more money by buying 70 texts for $10 and just texting.
I bought a 5-pound Vodafone "TopUp" voucher with cash and entered the 12-digit code it came with on my phone to add more money to the SIM card. The vouchers also are available via ATMs for the banks HSBC, Lloyds, TSB, Natwest or Royal Bank of Scotland. You can alternatively register your credit card with Vodafone and add minutes by texting.
Step 3: The road test. And: What about switching back?
The phone worked without a hitch. It was nice to be able to give people in the U.K. a local phone number for their convenience and also store their incoming numbers on my own phone. Also, phone numbers provided when calling information can be texted to your phone. That may not seem like much, but it can be much easier than struggling to scribble down a four-digit exchange and six-digit number dispatched by a fast-talking operator.
Upon returning home, I was a little nervous: Nobody from either AT&T or Vodafone told me how to switch back to my original service. Upon landing in New York, I simply removed the Vodafone SIM card, put my AT&T SIM card back in and powered on the phone. After a few minutes, my phone reconnected with the local network and I was back to my old service.
Things to consider
Your phone must be compatible with one of the networks used in the country you're visiting. My Cingular 8525 (AT&T 8525) is compatible with GSM 850/900/1800/1900; EDGE; UMTS and HSDPA. The major mobile carriers in the U.K. use GSM 900, GSM 1800 and 3G networks, so there was no problem.
Finally, there's no guarantee that your carrier or phone manufacturer will be cooperative in handing over the unlock code for your phone. A little extra patience while on the phone with the customer service representative and giving your carrier plenty of notice before your trip will likely help.


Thanks
Good Luck

"Don't Forget to rate the solution"

i wnt unlock code as i have forgot my code?