What is USSD
USSD stands for Unstructured Supplementary Service Data – the tech behind those quick menus you get when you dial a code like *121# or *99# on any phone, smartphone or not. Unlike an app or even SMS, USSD opens a live session straight to your operator’s network: you dial, a menu pops up, you reply with a number, and it walks you through – checking balance, buying a recharge, or even doing a bank transfer – all in real time, with no internet needed.
How does USSD work
USSD works completely differently from SMS, even though both ride on the same signalling channel. SMS is store-and-forward – your operator’s SMSC holds the message and delivers it whenever the recipient’s phone is reachable, so there’s always a small delay. USSD is session-based and real-time instead: the moment you dial *121#, a live connection opens between your phone and the operator’s USSD gateway, and it stays open until you finish or it times out from inactivity. Each screen you see is generated on the fly by whatever service sits behind that short code, and your reply sends the next request in the same session – back and forth, like a conversation. Because it rides on signalling channels rather than data, USSD works on any handset, feature phone or smartphone, with zero internet and no app to install. That’s exactly why it’s stayed central to mobile banking in India – NPCI’s *99# service lets anyone do a UPI transfer from a basic phone, and telcos use the same mechanism for instant balance checks and recharges.
How OneXtel helps with USSD
USSD gateway and short-code operation isn’t something OneXtel runs – that’s a telecom-operator-level service, not a CPaaS product, and we’re upfront about that rather than stretching the truth. Where OneXtel fits in is right after the USSD session ends: think of a customer dialling *99# to check a bank balance or complete a UPI transfer, then needing a written confirmation for their records. That’s where OneXtel’s transactional SMS comes in – firing off a DLT-compliant confirmation or receipt the moment the USSD session closes, over the same Sender ID and template infrastructure used for OTPs and alerts. Because that SMS layer sits on the same platform as WhatsApp, Voice/IVR, RCS, email and push, a business running USSD-triggered flows can just as easily follow up on WhatsApp or a voice call instead, without building a separate integration for each channel.
Why it matters
USSD still reaches people that apps and even SMS sometimes can’t – anyone on a feature phone, anyone with a dead data connection, anyone in a low-coverage area where a session-based, signalling-level connection gets through more reliably than a data packet. That’s a huge chunk of India’s mobile users, which is exactly why NPCI built *99# as a UPI channel in the first place, not just an operator convenience. For a business, that means USSD-adjacent flows – balance checks, banking, recharges – are still worth planning around, even in an app-first world. And whatever happens inside that USSD session, what happens right after – a confirmation, a receipt, a follow-up offer – is where a CPaaS platform like OneXtel actually earns its place.