Direct phone STK configured
  Public URL:  https://net.pamnetsolutions.co.ke
  Callback:    https://net.pamnetsolutions.co.ke/payments/mpesa-callback
  Environment: live
  Demo STK:    off

Callback check: OK — HTTPS callback OK
Resolved callback: https://net.pamnetsolutions.co.ke/payments/mpesa-callback
OAuth: OK — Daraja OAuth OK (live)

Ensure net.pamnetsolutions.co.ke points to this server with HTTPS.
Buy a package — the customer phone should get the M-Pesa PIN prompt directly.