Setup Guide
Whether this needs a fresh certificate or just a portal-level update depends on what exactly changed.
Your DSC certificate itself is tied to your identity (PAN, name), not directly to a specific mobile number or email, those are typically stored in your portal account profile (MCA, GST, Income Tax, etc.) or with your Certifying Authority for communication purposes, separate from the certificate's technical contents.
For your portal login profile (like your MCA or GST account's contact details), update it directly in that portal's profile settings, this doesn't require a new DSC. For your Aadhaar-linked mobile used during eKYC verification, that needs to be updated with UIDAI directly, and matters if you're renewing or reissuing your DSC, since eKYC depends on it.
If your name itself changed (not just contact details), you'd need a fresh DSC reflecting the updated identity, since the certificate is bound to your verified name and PAN.
We can clarify which specific change you need, a portal profile update or a fresh certificate, and help with either.
No, if only your contact details changed, update them in your portal account profile directly, this doesn't require reissuing your certificate.
Yes, particularly for renewal, since eKYC verification depends on OTP delivery to that number, keep it updated with UIDAI.