Steve1980
Regular Member
There's lots of useful information on the forum about band and cell locking but I thought it might be helpful to write up a guide pulling it into one place. This write-up is more "I did it this way, and here's how you can too" and not "This is the best way to do it, so do it this way!".
I am not an expert but I've been playing around with this a lot recently, specifically in the context of Three UK 5G with a ZTE MC888. I hope a lot of the concepts I've learned are fairly general but if I've got something wrong please let me know. Experts: I am trying to write for a general audience so please accept my apologies if I've brushed complexity under the carpet.
Why use band or cell locking?
If you are happy with your connection, you probably don't need to. If your connection is fine but you like tinkering, you might be able to get an even better connection or you might enjoy learning more about the network in your area.
Band or cell locking is most useful if you can't get a decent connection. I got my shiny new 5G home broadband and it worked great for a couple of days on the automatic settings, then downgraded to unusably slow (<2Mbit/s download) 4G broadband. Cell locking has (touch wood) got me back to a fast and reliable 5G connection.
Experimenting with band or cell locking can be tedious, but when you suddenly get a solid 5G connection it's very rewarding!
Is this safe?
Probably. Take some screenshots of your router's web GUI and/or export the settings to a file before you start playing around. That way if you have to factory reset it you can put things back how they were.
I suspect band locking is safer than cell locking. I did manage to soft-lock my router using cell locking, but taking the SIM out and then doing a factory reset sorted it out. Still, proceed with caution and (naturally) at your own risk.
Why do you keep talking about 4G? I want a 5G connection!
Most UK 5G connections use 5G NSA (non-standalone), which means the 5G connection piggybacks on a 4G connection. That 4G connection has a lot of influence on the 5G connection (if any) and how it performs, so this post is all about 4G band/cell locking. Don't be misled; this is very relevant to getting a good 5G connection, as well as optimising your 4G connection if you are in an area without 5G.
It is possible to do band/cell locking for the 5G part of 5G NSA and for 5G SA (standalone), but I don't have any experience with that so it isn't covered here.
The network cake shop
The mobile network near you is made up of lots of cells. Some of those cells will work better than others, for a variety of reasons. By default your router will look at the cells it can see and pick one for you. In general it will make a good (if not optimal) choice, your connection is fine and you're happy. Sometimes it won't make a good choice and you need to help it make the decision.
Let's pretend for a moment the network is like a cake shop. On the counter in front of you are dozens of cakes of different colours and types.
Not using cell or band locking is like saying to the baker: "I'd like a cake, please. I don't mind which, you pick one you think I'll like."
Using cell locking is like saying: "I'll have that lemon drizzle cake over there."
Band locking is a sort of halfway house, where you are only allowed to talk about colours. You can say "I'll have a yellow cake" or "I'll have a red, green or blue cake", but that's all. The baker picks you a cake that is a colour you specified, based on what he thinks you'd like.
Band locking is easier, because your choice is limited and relatively simple: you don't need to know what a lemon drizzle cake is or how it differs from a lemon tart. But it also gives you less control: if you want a lemon drizzle cake, you can't ask for it directly. You can only tilt the odds in your favour by saying things like "I want a yellow cake", and you might end up with a custard slice.
So in this analogy, the colour of a cake is like the band used by a network cell. The baker plays the role of the router.
The cake shop's special offer
It's actually more complex (but better) than this. The cake shop has a special offer, where they sometimes (not always) give you some additional cakes along with first cake. You never get to pick these yourself; the baker picks them. The only catch is that all the cakes you get have to be different colours.
This is carrier aggregation. A 4G connection typically uses more than one band - one of them is the primary band, and there can be several additional secondary bands. Not all bands are equal, but in general adding an extra band to your connection makes it better.
If you don't use cell or band locking, the baker will pick a cake or cakes, all of different colours, that he thinks you'll like.
If you use cell locking, you pick one cake out, and the baker may pick some others of different colours for you as well.
If you use band locking, you get a cake or cakes picked by the baker, and none of them can be a colour you said you didn't want.
This is another downside to band locking. If you were trying really hard to get given a lemon drizzle cake by saying "I only want a yellow cake", you won't get any extras. If you compromise and say "I want a yellow or red cake", you are less likely to get the lemon drizzle cake you really wanted, but you are still in with a chance, and you might get both a yellow cake and a red cake. You might just get a red cake on its own, though.
What's a band, anyway?
Let's drop the analogy and start using the right terminology.
A band is a range of radio frequencies used to send or receive data. Bands are given arbitrary but standardised numbers and assigned by regional authorities to different network operators. For example, in the UK Three uses bands 1, 3, 20, 28 and 32. These band numbers are probably what you will see when using your router's band locking feature.
Bands can also be referred to by their frequency (for example, band 20 is 800MHz) or by an EARFCN (for example, Three's band 28 is EARFCN 9360). There are lots of websites that will help you convert between these different conventions, such as this one. (Search for your network at the top to make it a lot more readable.)
Your router's network information page will probably use a mix of these ways to refer to bands and it may take some experimentation to work out what's what. I've included some notes for the ZTE MC888 below.
Using band locking
I suggest you try band locking first even if you plan to move on to cell locking later, as it will reveal some useful information about the nearby cells.
Start by finding the bands used by your network; check a few websites because there can be outdated information around. As noted above, Three UK currently uses bands 1, 3, 20, 28 and 32, so that's five different bands.
Your router's 4G band locking controls will allow you to enable or disable each different band individually. You can ignore bands not used by your network, as it won't make any difference whether they are enabled or disabled anyway.
You need to test different combinations of bands being enabled/disabled. For each combination, make sure your change to the band lock settings has been applied and then test the resulting connection. You may get no connection at all, you may get 4G or 5G. If you have a connection, do a speed test - don't just assume that all 4G connections are equally good, all 5G connections are equally good or that 5G is always better than 4G.
Keep notes as you test different combinations. Once you've finished, you can change the settings back to whichever combination worked best. If you can't or don't want to move on to cell locking, you're done.
If you might want to try cell locking afterwards, it will be helpful to check the network information in your router's web GUI and note down the cell ID, PCI and EARFCN of the cells the router picks with each band lock combination. Your router may only show the details for the primary cell, which is good enough, but if it shows the details for the secondary cells as well that is even better.
What band combinations should I try?
I suggest starting off by testing combinations where:
If you don't find a good combination that way, or if you're keen to see if you can find an even better one, you could simply try all possible combinations. If your network has n bands, there are 2^n combinations to try. So for Three with 5 bands that's 2^5=32 combinations, which is tedious but manageable. You don't need to test the combination with no bands enabled and you've probably already been testing with all bands enabled before you started band locking.
If you like, you can use this site to generate all the possible combinations of bands to try out.
I am not an expert but I've been playing around with this a lot recently, specifically in the context of Three UK 5G with a ZTE MC888. I hope a lot of the concepts I've learned are fairly general but if I've got something wrong please let me know. Experts: I am trying to write for a general audience so please accept my apologies if I've brushed complexity under the carpet.
Why use band or cell locking?
If you are happy with your connection, you probably don't need to. If your connection is fine but you like tinkering, you might be able to get an even better connection or you might enjoy learning more about the network in your area.
Band or cell locking is most useful if you can't get a decent connection. I got my shiny new 5G home broadband and it worked great for a couple of days on the automatic settings, then downgraded to unusably slow (<2Mbit/s download) 4G broadband. Cell locking has (touch wood) got me back to a fast and reliable 5G connection.
Experimenting with band or cell locking can be tedious, but when you suddenly get a solid 5G connection it's very rewarding!
Is this safe?
Probably. Take some screenshots of your router's web GUI and/or export the settings to a file before you start playing around. That way if you have to factory reset it you can put things back how they were.
I suspect band locking is safer than cell locking. I did manage to soft-lock my router using cell locking, but taking the SIM out and then doing a factory reset sorted it out. Still, proceed with caution and (naturally) at your own risk.
Why do you keep talking about 4G? I want a 5G connection!
Most UK 5G connections use 5G NSA (non-standalone), which means the 5G connection piggybacks on a 4G connection. That 4G connection has a lot of influence on the 5G connection (if any) and how it performs, so this post is all about 4G band/cell locking. Don't be misled; this is very relevant to getting a good 5G connection, as well as optimising your 4G connection if you are in an area without 5G.
It is possible to do band/cell locking for the 5G part of 5G NSA and for 5G SA (standalone), but I don't have any experience with that so it isn't covered here.
The network cake shop
The mobile network near you is made up of lots of cells. Some of those cells will work better than others, for a variety of reasons. By default your router will look at the cells it can see and pick one for you. In general it will make a good (if not optimal) choice, your connection is fine and you're happy. Sometimes it won't make a good choice and you need to help it make the decision.
Let's pretend for a moment the network is like a cake shop. On the counter in front of you are dozens of cakes of different colours and types.
Not using cell or band locking is like saying to the baker: "I'd like a cake, please. I don't mind which, you pick one you think I'll like."
Using cell locking is like saying: "I'll have that lemon drizzle cake over there."
Band locking is a sort of halfway house, where you are only allowed to talk about colours. You can say "I'll have a yellow cake" or "I'll have a red, green or blue cake", but that's all. The baker picks you a cake that is a colour you specified, based on what he thinks you'd like.
Band locking is easier, because your choice is limited and relatively simple: you don't need to know what a lemon drizzle cake is or how it differs from a lemon tart. But it also gives you less control: if you want a lemon drizzle cake, you can't ask for it directly. You can only tilt the odds in your favour by saying things like "I want a yellow cake", and you might end up with a custard slice.
So in this analogy, the colour of a cake is like the band used by a network cell. The baker plays the role of the router.
The cake shop's special offer
It's actually more complex (but better) than this. The cake shop has a special offer, where they sometimes (not always) give you some additional cakes along with first cake. You never get to pick these yourself; the baker picks them. The only catch is that all the cakes you get have to be different colours.
This is carrier aggregation. A 4G connection typically uses more than one band - one of them is the primary band, and there can be several additional secondary bands. Not all bands are equal, but in general adding an extra band to your connection makes it better.
If you don't use cell or band locking, the baker will pick a cake or cakes, all of different colours, that he thinks you'll like.
If you use cell locking, you pick one cake out, and the baker may pick some others of different colours for you as well.
If you use band locking, you get a cake or cakes picked by the baker, and none of them can be a colour you said you didn't want.
This is another downside to band locking. If you were trying really hard to get given a lemon drizzle cake by saying "I only want a yellow cake", you won't get any extras. If you compromise and say "I want a yellow or red cake", you are less likely to get the lemon drizzle cake you really wanted, but you are still in with a chance, and you might get both a yellow cake and a red cake. You might just get a red cake on its own, though.
What's a band, anyway?
Let's drop the analogy and start using the right terminology.
A band is a range of radio frequencies used to send or receive data. Bands are given arbitrary but standardised numbers and assigned by regional authorities to different network operators. For example, in the UK Three uses bands 1, 3, 20, 28 and 32. These band numbers are probably what you will see when using your router's band locking feature.
Bands can also be referred to by their frequency (for example, band 20 is 800MHz) or by an EARFCN (for example, Three's band 28 is EARFCN 9360). There are lots of websites that will help you convert between these different conventions, such as this one. (Search for your network at the top to make it a lot more readable.)
Your router's network information page will probably use a mix of these ways to refer to bands and it may take some experimentation to work out what's what. I've included some notes for the ZTE MC888 below.
Using band locking
I suggest you try band locking first even if you plan to move on to cell locking later, as it will reveal some useful information about the nearby cells.
Start by finding the bands used by your network; check a few websites because there can be outdated information around. As noted above, Three UK currently uses bands 1, 3, 20, 28 and 32, so that's five different bands.
Your router's 4G band locking controls will allow you to enable or disable each different band individually. You can ignore bands not used by your network, as it won't make any difference whether they are enabled or disabled anyway.
You need to test different combinations of bands being enabled/disabled. For each combination, make sure your change to the band lock settings has been applied and then test the resulting connection. You may get no connection at all, you may get 4G or 5G. If you have a connection, do a speed test - don't just assume that all 4G connections are equally good, all 5G connections are equally good or that 5G is always better than 4G.
Keep notes as you test different combinations. Once you've finished, you can change the settings back to whichever combination worked best. If you can't or don't want to move on to cell locking, you're done.
If you might want to try cell locking afterwards, it will be helpful to check the network information in your router's web GUI and note down the cell ID, PCI and EARFCN of the cells the router picks with each band lock combination. Your router may only show the details for the primary cell, which is good enough, but if it shows the details for the secondary cells as well that is even better.
What band combinations should I try?
I suggest starting off by testing combinations where:
- each band is enabled in isolation (so for Three, band 1 and nothing else, then band 3 and nothing else, etc)
- each band is disabled in isolation (so for Three, bands 3+20+28+32, then bands 1+20+28+32, etc)
If you don't find a good combination that way, or if you're keen to see if you can find an even better one, you could simply try all possible combinations. If your network has n bands, there are 2^n combinations to try. So for Three with 5 bands that's 2^5=32 combinations, which is tedious but manageable. You don't need to test the combination with no bands enabled and you've probably already been testing with all bands enabled before you started band locking.
If you like, you can use this site to generate all the possible combinations of bands to try out.























