How a GST number leads to a mobile number and email

The GST portal’s own user manual for a new registration lists what Part A of the application asks for before anything else: the state and district, the legal name as it appears in the PAN database, the PAN itself, which the manual calls mandatory, the email address of the primary authorised signatory, and the mobile number of the primary authorised signatory. The manual then says that different one-time passwords are sent to the email address and the mobile number for authentication, and the application cannot proceed until both are entered.

So the contact on a GST registration is not an optional extra. It is the first thing the registration was built on, and it was verified at the time. It belongs to the primary authorised signatory: in a proprietorship that is usually the owner; in a company it is often a director or the head of accounts; and for many small businesses it is the chartered accountant or consultant who filed the application.

The Search Taxpayer page on the GST portal can be used without logging in. The manual for it lists what you get: the GSTIN or UIN, the legal name of the business, the trade name, the effective date of registration, the constitution of business, the principal place of business, the date of cancellation where there is one, and details of returns filed. The mobile number and the email address are not among them.

That is a deliberate line. The public search exists so that a buyer can confirm a supplier’s registration before paying an invoice, and that needs the name, the status and the address. It does not need a phone number, so the portal does not give one.

Services that advertise a “GST to phone number” lookup answer the question the portal will not: given a GSTIN, what is the registered mobile and email. gstinapi.in offers this as the Contact option of its Bulk GSTIN Check, through a verification provider rather than the GST network. Upload a spreadsheet of GSTINs and it comes back with Registered Mobile and Registered Email filled in, alongside the legal name, status and address read from the GST network, and a status column.

Two things to expect from an honest version of this. First, there is a “no contact on record” outcome, because not every GSTIN has a contact the provider can return, and a service that promises one for every number is overstating. Second, it only runs one way. There is no lookup from a mobile number to a GSTIN on gstinapi.in.

The registration details themselves, the legal name and whether the registration is active or cancelled, do not come from the same place. They are read live from the GST network by the Search and Profile options. A contact lookup tells you how to reach a business; it does not tell you whether that business is still registered.

The useful cases are the ones where you already hold a GSTIN for a business reason and need to reach the business behind it. A new vendor to confirm before the first purchase order. A customer whose invoice is overdue and whose only reliable identifier is the GSTIN on it. A know-your-business check where a document names a party and you need to establish that someone answers for it.

A mobile number and an email address belong to a person. India’s Digital Personal Data Protection Act, 2023 defines personal data as any data about an individual who is identifiable by or in relation to it, and section 4 allows personal data to be processed only for a lawful purpose, with the individual’s consent or for the legitimate uses the Act lists. A proprietor’s mobile number is personal data under that definition. In practice that means: use the contact for the business purpose you looked it up for, keep it to that purpose, and do not turn a list of GSTINs into a list of people to message who have no relationship with you.

gstinapi.in’s page for the feature says the same thing. The Contact option is for verification and collections, not for lead lists.

• It does not prove identity. The number on record is whoever the business named as its primary authorised signatory when it registered, which can be a consultant.
• It can be stale. A business that changes its phone number is supposed to amend its registration; many do not, and the old number stays on record.
• It does not say whether the registration is active. Run the Search or Profile option, which reads the GST network live, when the status matters.
• It is not reversible. A phone number does not lead to a GSTIN.

1. Sign in, open Bulk GSTIN Check in the dashboard, and choose Contact.
2. Upload an .xlsx file with a GSTIN column. If the sheet already has a Mobile or Email column, those are filled in place; otherwise two columns are added.
3. Download the result. Rows with no contact on record say so in the status column; malformed and not-found GSTINs are marked and not charged.

The price depends on the account’s pack: 4 credits per GSTIN on Scale or Business, 6 on Starter or free credits, which is ₹1.60, ₹2.00 and ₹4.80 at those packs’ per-credit rates. A GSTIN with no contact on record is charged, because the lookup was made.