Setup of SIM900 Shield

[Tom_G_2010]

My SIM900 Shield just arrived and I am now reading through the wiki in preparation for setting it up. I have two quick questions that I don't see addressed in the wiki. My apologies if I have missed something in my reading.

1. On the back of the circuit board there is a battery holder for a CR1220. I see no mention of it in the documentation. Is the battery optional or required, and what function does it serve?

2. The documentation does not specify what size sim card to use. I went on line to order a sim card and there are four sizes listed: Standard; Mini; Micro and Nano. As best I can tell from measuring the card cage and looking up sim card dimensions on line I should be ordering a mini, yes? Can you please confirm this,

Thanks!
Tom G.

[Alex-w]

hi Tom G：
1.no，it serve RTC
2.Standard

[Tom_G_2010]

Thanks!