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Unlocking, size? links & help

Unlocking    Which SIM size?    About the SIMs   Links   Glossary

Unlocking handsets

Of course to use your SIM in a handset it needs to be;
  • SIM Free
  • unlocked
  • compatible SIM with the carrier network 
If your handset comes up - enter unlock code or similar and you don't usually see this - it means it's probably locked.

There are many online offers for phone unlocking. Here's one we have found reliable in the past;


There's a great source of unlocking reference, info, ratings and links here.

For example usually the following 
Mobile Virtual Network Operators (MVNOs) SIMs will work with the Mobile Network Operators (MNOs);

Lebara = Vodafone
Lyca = O2
Virgin = T Mobile
Giffgaff = O2
Now = Orange
Vectone = T Mobile
Delight = T Mobile

Which SIM size?

Full, Mini (or standard), Micro & Nano shown above

Here is a list of common devices that need the following SIM sizes;

  • iPhone5
  • iPad 3
  • iPad Mini
  • iPad Air


·        Acer CloudMobile S500
·        Acer Liquid C1
·        Acer Liquid Gallant E350
·        Acer Liquid mini E310
·        Apple iPhone
·        Apple iPhone 4
·        Apple iPhone 4 CDMA
·        Apple iPhone 4S
·        Apple iPhone 4S 16GB
·        Apple iPhone 4S 32GB
·        Asus Fonepad
·        Asus PadFone 2
·        BlackBerry Curve 9220
·        BlackBerry Curve 9320
·        BlackBerry Q10
·        BlackBerry Q10
·        BlackBerry Z10
·        HTC Butterfly
·        HTC Desire VT
·        HTC Desire X
·        HTC DROID DNA
·        HTC First
·        HTC J
·        HTC One
·        HTC One SC
·        HTC One ST
·        HTC One SV
·        HTC One SV CDMA
·        HTC One VX
·        HTC One X+
·        HTC Windows Phone 8S
·        HTC Windows Phone 8X
·        HTC Windows Phone 8X CDMA
·        Huawei Ascend G615
·        Huawei Ascend P2
·        Huawei Ascend W1
·        Huawei Ascend Y300
·        Huawei Premia 4G M931
·        LG Escape P870
·        LG Escape P870
·        LG Intuition VS950
·        LG Lucid 4G VS840
·        LG Mach LS860
·        LG Motion 4G MS770
·        LG Nexus 4 E960
·        LG Optimus 3D Cube SU870
·        LG Optimus 3D Max P720
·        LG Optimus 4X HD P880
·        LG Optimus Elite LS696
·        LG Optimus G E970
·        LG Optimus G E975
·        LG Optimus G LS970
·        LG Optimus G Pro E985
·        LG Optimus L5 E610
·        LG Optimus L7 P700
·        LG Optimus L9 P760
·        LG Optimus L9 P769
·        LG Optimus LTE2
·        LG Optimus M+ MS695
·        LG Optimus True HD LTE P936
·        LG Optimus Vu II
·        LG Optimus Vu II F200
·        LG Optimus Vu P895
·        LG Spectrum II 4G VS930
·        LG Splendor US730
·        LG T385
·        LG Xpression C395
·        Motorola ATRIX HD MB886
·        Motorola ATRIX TV XT682
·        Motorola Defy Pro XT560
·        Motorola DEFY XT XT556
·        Motorola DROID RAZR HD
·        Motorola DROID RAZR M
·        Motorola DROID RAZR MAXX HD
·        Motorola Electrify 2 XT881
·        Motorola Electrify M XT905
·        Motorola MotoGO EX430
·        Motorola Motosmart Flip XT611
·        Motorola Motosmart Me XT303
·        Motorola MOTOSMART MIX XT550
·        Motorola RAZR HD XT925
·        Motorola RAZR i XT890
·        Motorola RAZR M XT905
·        Motorola RAZR V MT887
·        Motorola RAZR V XT885
·        Motorola RAZR V XT889
·        Motorola XT760
·        Nokia Lumia 520
·        Nokia Lumia 720
·        Nokia Lumia 925
·        Nokia Lumia 928
·        Samsung Galaxy Discover S730M
·        Samsung Galaxy Exhibit T599
·        Samsung Galaxy Fame
·        Samsung Galaxy Grand I9080
·        Samsung Galaxy Mega 5.8 I9150
·        Samsung Galaxy Mega 6.3 I9200
·        Samsung Galaxy Note 8.0 N5100
·        Samsung Galaxy Note II
·        Samsung Galaxy Pop SHV-E220
·        Samsung Galaxy S III std & LTE
·        Samsung Galaxy S III Mini                   
·        Samsung Galaxy S4 16GB
·        Samsung Galaxy S4 CDMA
·        Samsung I9305 Galaxy S III
·        Samsung I9500 Galaxy S4
·        Samsung I9505 Galaxy S4
·        Sony Ericsson Live with Walkman
·        Sony Ericsson txt
·        Sony Ericsson W8
·        Sony Ericsson Xperia Arc
·        Sony Ericsson Xperia Arc S
·        Sony Ericsson Xperia mini
·        Sony Ericsson Xperia mini pro
·        Sony Ericsson Xperia Neo
·        Sony Ericsson Xperia neo V
·        Sony Ericsson Xperia PLAY CDMA
·        Sony Tablet P
·        Sony Xperia acro HD SO-03D
·        Sony Xperia acro HD SOI12
·        Sony Xperia acro S
·        Sony Xperia E
·        Sony Xperia E
·        Sony Xperia go
·        Sony Xperia GX SO-04D
·        Sony Xperia ion HSPA
·        Sony Xperia ion LTE
·        Sony Xperia J
·        Sony Xperia neo L
·        Sony Xperia P
·        Sony Xperia S
·        Sony Xperia SL
·        Sony Xperia sola
·        Sony Xperia SP
·        Sony Xperia SX SO-05D
·        Sony Xperia T
·        Sony Xperia T LTE
·        Sony Xperia Tablet Z LTE
·        Sony Xperia tipo
·        Sony Xperia TX
·        Sony Xperia U
·        Sony Xperia V
·        Sony Xperia Z
·        Sony Xperia ZL
·        Sony Xperia ZR
·        Sony Xperia™ miro
·        Sony Xperia™ U
Apple iPad 2


All other models not listed (unless very new of course!)

About the SIM

The Subscriber Identity Module is a portable microprocessor in a smart card for use in mobile phones.

SIM cards store the required information to identify the mobile device. It has an identifier that ties it to the CTN (Cellular Telephone Number) or MPN (Mobile Phone Number).

It also contains data required for voice encryption to make listening in on calls almost impossible (except when the wireless carrier itself or an organisation with access to the network is doing the eavesdropping).

In this way the customer ID (and personal number) is tied to the SIM card and not to a certain mobile phone, which was a limitation of analogue devices which used an ESN (Electronic Serial Number). This allows for a seamless interchange of the same SIM card and therefore portable number, between different GSM mobile phones. At one time some UK networks (Vodafone) allowed multiple SIM serials sharing one number!

SIM cards also serve as storage for SMS messages and the user's contacts. Current SIM cards can store up to 250 name/number pairs and up to 50 SMS text messages.

The SIM card cannot store multiple numbers per contact or other more complex information. This means that if you copy your contacts info from the phone memory to the SIM memory, contacts get broken up into as many entries as there are numbers for each individual contact and discards the other information.

All GSM phones (and most iDEN phones) require a SIM card to operate. There are certain types of phones (CDMA, TDMA, AMPS) that do not use a SIM. Instead, the required data is programmed directly into the phone.

The SIM cards come in four standard sizes:

·        Full-size (85.6mm × 53.98mm × 0.76 mm)

·        Mini-SIM often refered to as 'Standard' (25mm x 15mm x 0.76mm)

·        Micro-SIM (15mm x 12mm x 0.76mm)

·        Nano-SIM (12.3mm × 8.8mm × 0.67mm)

·        Embedded-SIM (surface mounted on a circuit board)

The first to appear was the full-size or 1FF (1st Form Factor), the size of a credit card (85.60 mm × 53.98 mm × 0.76 mm), which appeared in 1991 and the UK in around 1992, with the launch of digital GSM. It was immediately followed by a Mini-SIM or 2FF (2nd Form Factor), which has the same thickness but is 25 mm long by 15 mm wide, with one of its corners cut to prevent mis-insertion. In 2003, (but not widely used until 2011) came Micro-SIM or 3FF (3rd Form Factor), with dimensions of 15 mm × 12 mm.

In 2012 the Nano-SIM or 4FF (4th Form Factor) was introduced, which measures 12.3 × 8.8 × 0.67 mm.

All SIM cards can use adapters to gain compatibility with devices with Micro-SIM and Mini-SIM slots. A Micro-SIM card can also be fitted in Mini-SIM slot with an adapter etc. however they are less relaible and loss of contact with the holder is a common fault, usually diagnosed by the device saying 'please insert SIM' or possibly 'SIM not allowed'.

There are two numeric passwords associated with a SIM card. One is the Personal Identification Number (PIN) that the user must input each time they start the device (this can be turned off via the phone settings).

When entering the PIN number the user has only three input attempts. If all three are incorrect, the card gets locked and a PUK (Personal Unblocking Key) must be entered in order for the card to work again. Only ten attempts to enter the PUK are permitted before the card is permanently locked and made.

The SIM serial number is in an organised smart card format (same as credit cards etc);

1 & 2 = Usage type = 89 for mobiles

3 & 4 = country code = 44 for UK issued

5 & 6 = network code = 00 for example = O2 Telefonica UK

7 onwards is the unique serial

Last digit is usually validated by something called a checksum. This is a complex calculation (e.g. Luhn algorithm) that produces a validating final digit to reduce casual fraud risks (not used by T-Mobile UK).


Useful Links

More about SIM cards;


Glossary of Mobile Terms;


HomeWhich SIM tariff ?£!Order FREE SIMsHow to Top-upTransfer your numberUnlocking, size? links & helpAgentsDownload International TariffsDownload Topup & Porting GuideAbout & Contact Us