Help Regarding TEL0051, GPS/GPRS/GSM Module V3.0

[quote]I've recently purchased a TEL0051, GPS/GPRS/GSM Module V3.0. I'm having some trouble getting it to work with my Arduino Mega 2560. I have tried the code, "How to drive the GSM Mode via USB port" - Send SMS, provided on the DF Robot Wiki page. The shield outputs the following:

---------------------Output------------------
+CFUN: 1
+CPIN: READY
GPS Ready
--------------------------------------------------

It stops and does not output Call Ready and it's not responsive to the AT Commands. Nonetheless, occasionally if I swap the Sim card, I will get a Call Ready response and AT Commands will work in a very small window, about 3 seconds. During that small window I've tried to quickly execute the AT Commands but I got no response. In addition, I tried the, How to Make a phone call code, where I executed the AT Command and similarly I don't get a response.

Would you mind helping me out because the sample code did not work for me. I really appreciate it. Thanks!

PS:
This is the DF Robot Wiki Page I used:
[url=http://www.dfrobot.com/wiki/index.php/GPS/GPRS/GSM_Module_V3.0_(SKU:TEL0051)]http://www.dfrobot.com/wiki/index.php/GPS/GPRS/GSM_Module_V3.0_(SKU:TEL0051)[/url][/quote]