# RC7620-1 PCM problem

**URL:** <https://forum.sierrawireless.com/t/rc7620-1-pcm-problem/25357>\
**Category:** RC76\
**Created:** [October 27, 2021, 8:31am UTC](https://forum.sierrawireless.com/t/rc7620-1-pcm-problem/25357 "2021-10-27T08:31:02Z")\
**Posts on this page:** 1\
**Showing post:** 10

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**Author:** ![nguyenducminh](https://avatars.discourse-cdn.com/v4/letter/n/a6a055/32.png) [@nguyenducminh](https://forum.sierrawireless.com/u/nguyenducminh)\
**Post date:** [November 8, 2021, 7:56am UTC](https://forum.sierrawireless.com/t/rc7620-1-pcm-problem/25357/10 "2021-11-08T07:56:21Z")

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Hi Matt,  
We used R8. We reported the issue of unresponsive AT command here:  
[UART AT Command hang when make a phone call - IoT Modules / RC76 - Sierra Wireless Forum](https://forum.sierrawireless.com/t/uart-at-command-hang-when-make-a-phone-call/24353/31)  
Please help us.  
Thank in advance,  
Minh

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