--- title: CDMA SIMs are compatible with HD devices only description: Due to changes made by Red Pocket Mobile's underlying carrier for the CDMA network, only HD compatible devices will be eligible for new activations after 4/30/2019. --- [Skip to content](https://help.redpocket.com/why-are-cdma-sims-only-compatible-with-hd-voice-capable-devices#main-content) English Show submenu for translations [Submit a ticket](https://help.redpocket.com/kb-tickets/new?hsLang=en) ![3.svg\]](https://help.redpocket.com/hubfs/3.svg) Open main navigation Close main navigation - English Show submenu for translations - [Submit a ticket](https://help.redpocket.com/kb-tickets/new) - [Go to redpocket.com](https://www.redpocket.com/) [Go to redpocket.com](https://www.redpocket.com/) RedPocket Mobile - There are no suggestions because the search field is empty. 1. [Help Center](https://help.redpocket.com/?hsLang=en) 2. [Device Support](https://help.redpocket.com/device-support?hsLang=en) 3. [Device Compatibility](https://help.redpocket.com/device-support?hsLang=en#device-compatibility) # CDMA SIMs are compatible with HD devices only When activating a CDMA network SIM, you must use an HD compatible device. This is due to changes made by RedPocket Mobile's underlying carrier for the CDMA network, effective 4/30/2019. HD Voice is an advanced calling feature that works only on the LTE network. It provides clearer call quality.  ##### **Is this change limited to RedPocket Mobile?** No. This change effects all MVNOs using the same underlying carrier as the RedPocket CDMA network. ##### **How do I know if my device is capable of HD voice?** To check if a phone is capable of HD voice, check the settings for the option to enable Advanced Calling or VoLTE. If the device does not support Advanced Calling/VoLTE, it is likely not HD Compatible on the CDMA network. ##### **What options do I have for my device if it is not HD voice compatible?** LTE compatible devices ***may*** work on one of RedPocket's other network options, like the GSMA network, with the insertion and activation of a [GSMA SIM](http://redpocket.com/plans). ##### Who is affected Customers who activated service before 4/30/2019 are not affected by this change. 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