From a user's perspective, it makes sense to "reuse" a 3G modem. Not only is it environmentally-friendly, it may help you save some money if the new service provider allows you to sign up without buying a new modem from them. In some cases, you might even want to use the older modem because it's faster or better in some way.
So after discontinuing my Maxis mobile broadband account, I decided to "reuse" the Huawei E1762 modem for my DiGi Broadband account. All I needed to do was pull out the old Maxis SIM card and insert the DiGi SIM card.
Of course, that's supposed to be the case. The reality is the Huawei E1762 modem was locked to the Maxis network. So this error message will pop-up if a non-Maxis SIM card is installed. Read more at TechARP.