Identify Three 4G band and 4G+ sites on ComReg SiteViewer

Thumbnail of ComReg SiteViewer map

The ComReg SiteViewer is a great way of identifying nearby masts, making it a lot easier to tell which side of the house to position a router or antenna.  While the map does not show band #s, the site IDs give very good clues as to whether Three is using band 3 or 20 and has multiple carriers (4G+). 

This can be essential when choosing an outdoor antenna and also before one starts drilling holes.  Band 3 is particularly important on Three as it offers double the bandwidth of band 20.  Most band 3 masts operate on three sectors, compared to just one or two for rural band 20 masts.

Before Three bought out O2 (Telefonica Ireland), the Three network only had 4G spectrum on 1800MHz, LTE band 3.  Once they merged with O2, they made extensive use of the acquired 800MHz spectrum (band 20) in rural areas.  They also operate some masts on the acquired 1800MHz spectrum from O2, but mainly in dense urban areas. 

Three 4G band and 4G+ indication

First let’s look at the 800MHz and 1800MHz each mobile network purchased:

Ownership of 4G spectrum in Ireland

On ComReg’s SiteViewer, sites that operate on Three’s original 4G spectrum (1800MHz only) have a Site ID that start with “THREE_”.  Such sites that list ‘LTE’ in the ‘Services’ operate on band 3 (1800MHz):

ComReg site with Site ID THREE_DO0167and services GSM, UMTS and LTE

Sites that operate on 4G spectrum acquired from the O2 purchase have a site ID that start with “3_”.  Such sites that list ‘LTE’ under ‘Services’ mostly operate on band 20 (800MHz):

ComReg site with Site ID 3_DO0167 and services GSM, UMTS and LTE

If there are two Three sites with the same Site ID number and both list ‘LTE’ under ‘Services’, that is a 4G+ mast.  In the two above screenshots, we can see that both sites end in ‘0167’, so this is a 4G+ site as there are clearly two LTE carriers. These 4G+ sites usually have 3 sectors on both carriers.

On masts that have a “3_” site ID with LTE, but where there the matching “Three_” site does not list ‘LTE’, this Three mast generally operates on 800MHz only.  This is also true for “3_” side IDs that have no “Three_” site ID, such as the following example:

ComReg site with Site ID 3_DO0041 and Service LTE

Three 3G band indication

Both Three and the former O2 network have 900MHz spectrum with extensive use of this band in rural areas.  Like the 1800MHz 4G band, the 2100MHz 3G band offers greater capacity than the 900MHz 3G band.  This makes it a great alternative to 4G in areas that have high contention. 

As 2100MHz frequencies do not penetrate walls that easily, most people that use 3G end up on the 900MHz 3G band that tends to also be congested.  With a good outdoor antenna, the router will generally use the 2100MHz band (if available) in 3G only mode.  I know a few who manage to get 10-20Mbps peak time on 3G where they could barely get over 1Mbps on 4G. A good example near me is Barnesmore in Co. Donegal.

The majority of “Three_” side IDs that list “UMTS” operate 3G on 2100MHz (Band 1), such as the following example:

ComReg site with Site ID THREE_DO0165 and services GSM, and UMTS

Where a “Three_” side ID lists “GSM” only, the corresponding “3_” site usually operates 3G on 900MHz (Band 8) only:

ComReg site with Site ID 3_DO0194 and service GSM.

Identifying the band by EARFCN

In dense urban areas, Three may operate some sites on the former O2 1800MHz band.  Such sites offer greater carrier aggregation capacity.  However, there does not appear to be a way of identifying such sites on the ComReg SiteViewer.

If you are within range of such a mast and have a 4G+ capable Android phone on the Three network, you can use an App like CellMapper or Network Cell Info to check the current and neighbour cell list EARFCN numbers.  In CellMapper, the EARFCN is shown on the row “(EA/UA/A)RFCN”. 

These are the EARFCNs Three uses:

  • 1700 – Band 3 (20MHz bandwidth, 1855MHz)
  • 1275 – Band 3 (15MHz bandwidth, 1812.5MHz)
  • 6300 – Band 20 (10MHz bandwidth, 806MHz)

In the above example, my phone shows 4G+ and lists a mixture of 1700 and 6300 for the EARFCN in the cells list. This means it is using both bands 3 and 20 for carrier aggregation.  However, if it lists a mixture of 1700 and 1275 for the EARFCN, it is using two band 3 cells for carrier aggregation.  Where it lists multiple cells for a single EARFCN, it is using the first cell listed for that EARFCN.

New forum for discussions

As many of my articles are heavily cluttered with comments asking for advice and help, I have set up a discussion forum to discuss about routers, antennas and mobile broadband. I will also post short articles from time to time on the forum, such as how to check the 4G band a Huawei router is using.

11 thoughts on “Identify Three 4G band and 4G+ sites on ComReg SiteViewer”

  1. Hi Sean,
    Great website.
    I wanted to post my own findings having recently installed an external directional 4G antenna (with Three sim in a router) at my holiday home in Donegal.
    My antenna posts directly at a Three mast with clear line of sight. The mast is probably 1 or 2 miles away.
    I get a 100% 4G signal showing on the router. Most of the time my download speeds are between 1-2 Mbps and sometimes going up to 8-9 meg in non peak times. My upload is consistently between 10-20 Mbps all of the time.
    If I change to 3G I might get slightly better download speeds of 6-7 Mbps but then poor Uploads of 1-2 Mbps.

    Am I right in thinking that the good upload speeds on 4g confirm I have everything aligned pretty well and I am just at the mercy of mast congestion and probable overloading causing my comparatively poor download speeds?

    1. It is quite likely either high contention on the mast or with the backhaul to it. Even on the Kilcar mast I’m connected to (also in Co. Donegal), the speed was dipping to 1-2Mbps this evening. The off-peak speed seems low however (I’d expect 20+Mbps for a strong signal), but there could be more people connected to it than the one here. If your router shows the SINR reading, that would be a good indication of how clean the signal is, i.e. it should be as positive as possible, preferably above 10.

      I wouldn’t worry about the upload speed on 3G unless you are uploading a lot of data. 6-7Mbps should have no problem streaming even in HD, assuming it’s a steady speed. Most people leave their router and phones connected in 4G, so this usually results in better 3G speed as most people would not think of trying 3G mode.

  2. Thanks for the reply.
    Unfortunately my router interface is very basic, it just gives my signal strength as a percentage and nothing more detailed than that.
    Out of interest, if you are getting similar 4g peak times to myself, do you stay on 3g or switch between the two?

    1. The 3G reception is very poor here, worse than 4G surprisingly. If I’m outside, I can pick up 4G fine (2-3 bar signal), but if I try dialling a number, the call will always fail and similarly I cannot receive calls as calls require 3G on the Three network. If I force my phone into 3G-only mode, it just says no service. I have a StellaDoradus 900MHz repeater and a directional antenna that gives me indoor 3G reception, however, with the weak 3G signal it manages to pick up, the 3G speed is poor, but at least usable for voice calls and receiving SMS verification codes.

  3. Thanks for all your handy tips Sean!

    I have a Huawei B525 connected via a pair of outdoor logperiodic antennas.
    These are positioned about 5 foot apart. One is 45 degreee off perpendicular, the other 90deg opposed. The mast is only a mile away but is obscured by trees.

    The signal indicator on the router home page keeps randonly jumping around.
    Between 1 and 4 bars. Occasionally 4G+ but mostly plain 4G.

    Any suggestions on how to get a steady 4G+? Since it is a lot faster!

    My son does online gaming and thinks there are regular drop outs.
    Router Switching bands???

    Any news about 5G data?
    I understand 3 are rolling it out locally. (Manorhamilton)
    Guess we’ll have to upgrade out modem/routers.

    1. It seems like it is jumping back and forth between two bands, likely band 20 and 3. Band 20 (800MHz) has much better penetration than band 3 (1800MHz) or the temporary 4G band 1 (2100MHz), but is generally congested as it has less bandwidth and the wider propagation means there are generally more connected to it. 4G+ is where your router aggregates the two bands together, however, the Huawei B525 doesn’t stay in 4G+ mode like most phones do.

      You can try using the Android App huaCtrl or the Windows utility LTEInspecteur to select individual bands. Try band 3 (1800MHz) to start with and run some speed tests, then repeat with band 1 (2100MHz). If band 1 shows no signal, then the mast there is not using it. With the huaCtrl phone App, you can try adjusting the antenna direction and height to see if you can improve the RSRP and SINR readings. E.g. An RSRP of -100dBm is better than -110dBm. For SINR, get the figure above 10 if you can.

      As 5G has poor penetration capability, I’m not sure if it will reach you if that mast obscured by trees will be upgraded for it. Three’s 5G coverage map is a rough guide and have heard reports of many people in the purple coverage areas not picking up a 5G signal even standing outside:

      I suggest waiting until Three launches their 5G broadband plans before looking for a 5G router. They have 5G restricted to specific phone handsets at this time of posting.

  4. Hi Sean,

    Super info here in this post, thank you.
    Are there a list of 4G+ routers or can I tell from the spec sheet on a standard 4G router if it’s capable of carrier aggregation?

    1. You can check whether a router is 4G+ capable based on its Cat rating. If it is Category 6 or higher, then it is 4G+ capable. If the router does not mention, then it’s likely Category 4 or lower, i.e. just regular 4G. Higher Category numbers such as 9 or higher may support 3 or more carrier aggregation. The following website shows what 4G bands popular routers and phones can aggregate:

  5. Hi Sean,
    Great site. Really helped me in choosing to go with Three LTE broadband and in choosing an outdoor antenna.

    Few questions. Given that Three have 2x20Mhz in the 1800Mhz band and they are, I think, noncontiguous, does that mean they have to be aggregated by the router, eg the B525?

    I’m looking at LTE A routers that can do 5 carrier aggregation and 256QAM like the Huawei 4G Router 3 Prime B818-263, and I’m wondering if the extra carrier aggregation would do anything for me.

    Can 3G bands be aggregated with 4G bands?

    As for 4×4 MIMO LTE, would such a router need 4 external antenna connectors? I can’t seem to find a router like this. It seems they don’t exist yet or apply more to 5G.

    Your thoughts on these questions would be greatly appreciated.

    1. The Huawei B525 unfortunately is unable to aggregate the two band 3 cells. I don’t think it can aggregate band 1 with 3 either, just 1 with 20 or 3 with 20. Three is currently using band 1 in some areas for 4G due to the temporary ComReg licence that lets them provision 3G band 1 for 4G use during the pandemic. They also have temporary spectrum on band 28, which they are operating in some areas. Both temporary bands are currently set to expire in October 2021.

      The newer Huawei B818 is capable of aggregating Three’s two band 3 cells and is also able to aggregate band 1 with 3. Unfortunately, Three has for some reason decided to refarm their 15MHz band 3 cell for 5G in some areas, so if the mast you’re picking up has both band 3 cells, it may lose the 15MHz band 3 cell at a later stage. This happened with the distant mast I’m connected to. On the other hand, the B818 is capable of aggregating bands 1, 3 and 20 (or 28), so if the mast you pick up operates 4G on band 1 or 28, you may get an improvement in speed. I’m not aware of any router (or phone) that can aggregate 3G with 4G.

      I have not come across any router with 4 external antenna connections, however, it is possible to mod the B818 to connect all 4 antenna leads. While I’ve come across plenty of guides and videos of this mod (including for the Netgear M1, etc.), so far I haven’t seen anyone report any significant improvement from connecting all 4 leads. There’s some discussion about this mod on the Huawei 5G routers (which don’t have active antenna sockets) in this forum thread.

  6. Thanks Sean.

    Very informative as ever. That’s interesting. I did not know the B525 wasn’t aggregating the two parts of the spectrum on band 3. I guess that could be a significant boost in speed if I could aggregate those with band 20.

    I’m connecting to Corn Hill which is a 4G+ site. It will be a long time before 5G arrives here in Leitrim. We might get it when 6G is all the buzz. Since the Corn Hill mast is in the middle of nowhere, I’m guessing or hoping Three will not refarm the 15Mhz on band 3 to 5G.

    Thanks again.

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