The BLU S1 was built for a network that no longer exists. Released in September 2017, it was the first BLU handset certified for Sprint. Sprint’s network was shut down in 2022. The S1 has no CDMA radio at all — it is a GSM and LTE device — and three of its LTE bands (25, 26 and 41) were Sprint’s. The bands it shares with AT&T and T-Mobile are still on the air, but whether the phone can actually place a call on them in 2026 comes down to VoLTE certification, and that is decided by the carrier, not the handset.
BLU S1 specifications
- Released — September 2017, at $179
- Display — 5.2-inch, 720 × 1280
- Chipset — MediaTek MT6750
- Memory — 2 GB RAM, 16 GB storage, microSD expandable
- Cameras — 13 MP rear, 5 MP front, 1080p video
- Battery — 2,800 mAh, non-removable
- Software — Android 7.0 Nougat
- Networks — GSM, HSPA and LTE. No CDMA.
- LTE bands — 2, 3, 4, 5, 7, 12, 17, 25, 26, 41
Why it stopped working
Two things happened, and the second one matters more than people expect.
Sprint went away. T-Mobile completed its merger with Sprint on April 1, 2020, retired the Sprint brand in August 2020, and shut down Sprint’s CDMA network and then its LTE network on June 30, 2022. Bands 25, 26 and 41 were the Sprint side of this phone. Nothing transmits on them for Sprint any more.
Then 3G went away, and calling changed. Older phones placed calls on 3G and used LTE only for data. With 3G shut down across the US carriers, every call now runs over LTE as VoLTE — and carriers only allow VoLTE from handsets they have certified. A 2017 device that was certified for Sprint is not automatically on AT&T’s or T-Mobile’s approved list. This is why a phone can show bars and still fail to complete a call.
Can you still activate a BLU S1?
On paper the radio overlaps the networks that are still running: band 2, 4 and 5 are used by AT&T, band 4 and 12 by T-Mobile. Band 13, Verizon’s primary LTE band, is missing, so Verizon and Verizon-based carriers are effectively out.
Do not buy a plan before you check. Dial *#06# to get the IMEI, give it to the carrier you want to join, and ask them to confirm the device is approved for activation and for VoLTE on their network. That single check settles it. Any carrier will run it for free, and a refurbisher who will not run it is not worth buying from.
If the answer is no
Where a former Sprint customer goes now
Sprint’s customers and spectrum went to T-Mobile; its prepaid brands went to DISH. Your number is portable either way, and it is the number that matters, not the handset.
Boost MobileBought Sprint’s prepaid business in 2020 — where former Sprint prepaid numbers landedSee port-out info
Compare every carrier228 US carriers and MVNOs, sorted by the network each one runs onBrowse the database
Is the BLU S1 a CDMA phone?
No. Despite being sold for Sprint, the S1 is GSM, HSPA and LTE only. It has no CDMA radio.
Will the BLU S1 work on T-Mobile or AT&T?
Its LTE bands overlap both, but overlap is not the same as approval. Give the IMEI to the carrier and ask whether the device is certified for activation and VoLTE. That answer is the only one that counts.
Will it work on Verizon?
Unlikely. The S1 does not support band 13, Verizon’s primary LTE band.
My old Sprint number still works. Where is it?
On T-Mobile, if the line stayed active. See how to switch carriers without losing your number.
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