These are the messages we received on new prepaid SIMs

When you purchase a new SIM and receive a new number, it does not always mean you are starting on a clean slate.
Following a series of messages we received on a new Vodacom contract SIM, we decided to see how new prepaid SIM cards were affected by advertising SMSs.
We purchased and registered four new prepaid SIM cards, one from Vodacom, Telkom, MTN, and Cell C, and installed them in four Samsung Galaxy S7 smartphones.
The SIM cards were loaded with airtime and then monitored from 10-21 July. The numbers of the prepaid SIMs were not given to anyone.
The activity recorded on each SIM over the of 11 days is detailed below, with initial SIM activation messages not included.
MTN
The MTN SIM received two “wrong number” calls in addition to a daily SMS regarding out-of-bundle data usage.
11 July: Call from Unknown Number
Wrong number
18 July: Call from Unknown Number
Wrong number
Every Day: SMS from MTN
Alert! Yesterday you used R1 on 1MB at Standard Data Rates! Buy a daily 20MB Bundle for only R4 by dialing *141*2*13311# now and SAVE BIG! TsCs.
Cell C
No messages or calls were received by the Cell C SIM.
Telkom
The Telkom SIM received the most SMSs, all of which were from Telkom.
11 July: SMS
We are excited that you chose to be part of Telkom’s prepaid plan that gives you MORE. We have rewarded you with R2.50 of free airtime to start your journey. Enjoy your gift. Free airtime expires in 7 days.
13 July: SMS
Hello!You have R12.50 FREE airtime available. R10.00 will expire on 17/07/2017.
13 July: SMS
Hello!You have 5 SMS/MMS available. 5 SMS/MMS will expire on 17/07/2017.
16 July: SMS
You can get R10 000 funeral cover when you recharge with R100 during the course of a calendar month. Reply with the world ‘FUNERAL’ to participate. Telkom has you covered from Hello to ‘Hamba Kahle’. Underwritten by Old Mutual. Ts&Cs apply.
16 July: SMS
FREE SMSes! Your gift today is 5 free SMSes. Free SMSes expire midnight today. Look out for tomorrow’s gift.
19 July: SMS
FREE SMSes! Your gift today is 5 free SMSes. Free SMSes expire midnight today.
Vodacom
The Vodacom SIM received automated advertising calls and an advertising SMS from a third-party.
13 July: Advertising Call
Automated voice call advertising welcome tones.
16 July: Missed Call from Unknown Number
19 July: Advertising Call
Automated voice call advertising welcome tones.
19 July: SMS from Unknown Sender
YOU WIN.:R750,000.00 from SUN LIGHT WASHING POWDER 2017 PROMO, your Ref/No. 019SA Call agent Mr James (Number removed) and claim.
Recycled numbers
Vodacom told MyBroadband that a common cause of advertising being sent to a new SIM was that its number had been recycled.
“When a number is recycled, the standard procedure is that we remove the number from Vodacom-owned distribution lists,” said Vodacom.
“Naturally, if the previous holder of the number signed up/registered for external marketing campaigns, Vodacom will have no knowledge or sight of these.”
Vodacom said the number of MyBroadband’s prepaid SIM had been recycled several times.
The company said that while it is also possible the spam message received was sent to a randomly-selected number, this is a very expensive marketing method.