看见TTY在用Tru Sim，就去它的网上看了一下，http://www.truphone.com/us/ 好象在美国可以免费接收短信
充值后多长时间作废网上没注明，于是给客户服务打电话。被告知：永远不作废，但有一个前提：私人账号不能连续六个月没有动静。
non usage of the sim for 6 months it will automatically be deactivated and the remaining balance will be forfeited. An account maintenance fee of $2 or 3 GBP will be observed. Also what you can do is atleast try to send an sms once in a while so that it will reflect on our end that you are still using the sim lets say in a span of 3 months.
听起来令人难以置信：$30买个卡，含$15充值，并跟来一个电话号码。你就有永远免费接收短信的功能了。在美国费用如下：
Call landlines cost per minute: $ 0.09
Call mobiles cost per minute: $ 0.09
Receive call/text cost per minute: $ FREE
Send a text cost per message: $ 0.09
Data per MB: $ 0.09
这么看来，除了免费接收短信这个功能，其它都比不上最近坛里网友sailfish发现的Lycamobile：通话费$0.05/分钟，数据$0.06/MB，短信$0.04/个，用手机查留言不收费！
How much does it cost to access the voicemail? Your Lycamobile Voicemail service has been automatically activated. To access your voicemail from your Lycamobile in the US dial 121 (or 91#). Calls to access the voicemail are absolutely free. Does Lycamobile charge taxes on my order? All charges are inclusive of tax. However, there may be required sales and similar taxes that are required by the state and are charged by the retailer where you purchased your Lycamobile products. There may also be various federal and state fees that Lycamobile must collect or that Lycamobile must pay as part of regulatory requirements that Lycamobile may pass on to its customers.
Lycamobile 的用户有人反映常有垃圾短信，这个比较头痛，每收到一条垃圾短信要花费$0.04。他们的客户服务也没有好的解决办法，不过似乎可以关闭短信功能：
How can I stop receiving unwanted texts or SPAM? When you receive a text from a company you have not given your number to, this is called SPAM. Unfortunately, Lycamobile is unable to prevent you from receiving these unwanted messages, unless you want to ban all text messaging. These companies have sophisticated ways of obtaining cell phone numbers. One way to avoid SPAM is to be careful about what sites you give your cell number to.
如此看来，两个服务都有最好，用Trusim接收短信，用Lycamobile接/打电话。估计用那些双SIM卡的手机做这个最合适了！
拿到了Lycamobile 的SIM卡，试验时发现个问题
Lycamobile 的留言是自动开启的。如果有人打你的手机并留言，要按分钟计时收费，留几分钟算几分钟，不管你的手机是否是关闭的。这样一来，前边说过的查手机留言不收费就没有什么优势了，因为在被留言的时候已经收过费了。
比较烦这个，我从来不愿意为广告垃圾留言付费。幸好他们有政策，就是只要你给客服打电话要求，就可以关闭留言。当然，关闭留言后，谁都无法给你留言。我的解决办法是，把号码捆绑到股哥语言（Google Voice），这样留言就用股哥语言免费查了。
如此看来，关闭短信和留言服务后，你就有一个$0.05/分钟的纯语音电话。
