cell phone

if you are using prepaid sim (儲值咭), no invoice will be sent to you unless you request (plus handling fee).

if you afraid, you can have 2 options:
1. buy a IDD calling card and use your mobile phone to dial the number according to your IDD calling card. The mobile phone will be shown as local calls only.
http://www.pccw.com/NASApp/cs/ContentServer?pagename=PCCW/PCCWHK/ProductsServices/ProductContent&cid=1007415925978&sectionid=1&pagelang=chi

2. buy a mobile prepaid SIM, like Peoples IDD 至抵傾儲值咭. replace your SIM card with your new sim card when you call your friends. Only $0.25/minute
http://www.peoples.com.hk/p_prepaid_iddtalk_charge_big5.jsp

簡單來說, 你可以用一般的 IDD 服務登記你的手提電話號碼, 例如 0060, 0080, 1666 等 ( 本人不是推薦你使用這幾間 ), 當你用手機打 IDD而使用該服務, IDD記錄不會在手提電話賬單出現 ( 除了用同一供應商送埋的就另計 如用 PCCW 3G+0060, 3HK+0080, 新世界 + 1678 .... ) 而是另外一張賬單. 如果要完全看唔到, 用 prepaid calling card 都 OK.

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