All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If we assume that these SIM cards do contain gold, then the amount will be very insignificant in addition to it being hidden and not apparent. Therefore, this does not prevent from using telephones.
Shaykh Ibn 'Uthaymeen in Ash-Sharh Al-Mumti':
"If a person says that the watch is not gold and it is not gold-plated, but in its machinery there is some gold; is it permissible (to wear it)?
Answer: “Yes, there is nothing wrong in it because if it is in the interior machinery and no one sees it or knows about it. If it is in the exterior machinery, such as the hand [of the watch] for example, then it is intended in itself (it is not bought for the gold in the hand), so there is no harm in using it.” [End of quote]
Allah knows best.