# SIM 7600 modem - no voice AT functionality?! **URL:** \ **Category:** General Guidance\ **Created:** [March 18, 2020, 9:16pm UTC](https://forum.arduino.cc/t/sim-7600-modem-no-voice-at-functionality/643147 "2020-03-18T21:16:44Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![lastchancename](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/lastchancename/32/215426_2.png) [@lastchancename](https://forum.arduino.cc/u/lastchancename)\ **Post date:** [March 18, 2020, 9:16pm UTC](https://forum.arduino.cc/t/sim-7600-modem-no-voice-at-functionality/643147/1 "2020-03-18T21:16:44Z")
I just received the first of a new batch of SIM 7600 4G shields. I run the same code as I use successfully on SIM5320 chips, but have noticed the 7600 boards don’t do _anything_ with the basic ATD, ATH commands, and don’t provide any incoming +CLIP or RING notifications. Everything else seems ok - for initialisation, interrogation and SMS text messaging in & out. Is there some extra magic setup, or a pin that has to be biased to enable the voice call signalling functionality ? ---
**Author:** ![Railroader](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/railroader/32/274550_2.png) [@Railroader](https://forum.arduino.cc/u/Railroader)\ **Post date:** [March 18, 2020, 9:24pm UTC](https://forum.arduino.cc/t/sim-7600-modem-no-voice-at-functionality/643147/2 "2020-03-18T21:24:25Z")
You need to tell what controller You intend to use. There's quite some difference between them. What do You want to achieve in Your proj? SMS is working. Audio is a difficult task. Reading Your Karma You're faar from a newbie. Second round.... ---
**Author:** ![lastchancename](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/lastchancename/32/215426_2.png) [@lastchancename](https://forum.arduino.cc/u/lastchancename)\ **Post date:** [March 18, 2020, 9:38pm UTC](https://forum.arduino.cc/t/sim-7600-modem-no-voice-at-functionality/643147/3 "2020-03-18T21:38:15Z")
Thanks @RR, this modem is stacked directly off a custom MEGA 1284 board on Serial1 I’m a little surprised, because all the other functionality has been/is working and has been rock solid with the 5320s for a couple of years..., and I have debugging prints wrapped around the serial I/O - so I know the various (voice control) messages are being sent and responses/notifications not received back. No OK, ERROR etc. Yet all the traffic for other commands are flying around exactly as they should. I’m not actually using the ADC/DAC audio _yet_, that’s a planned feature, but I do acknowledge incoming RING and CLIP notifications, and initiate outgoing confirmation calls with ATD; and ATH (unanswered ’free’ calls !) ---
**Author:** ![Railroader](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/railroader/32/274550_2.png) [@Railroader](https://forum.arduino.cc/u/Railroader)\ **Post date:** [March 18, 2020, 9:47pm UTC](https://forum.arduino.cc/t/sim-7600-modem-no-voice-at-functionality/643147/4 "2020-03-18T21:47:45Z")
You're using devices way beyond my experience. You know a lot more than I do. Getting the 7600 board working seams to be the issue. Dig deaper in the documentation of the 7600 board and hopefully find an unsupported demand. ---
**Author:** ![lastchancename](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/lastchancename/32/215426_2.png) [@lastchancename](https://forum.arduino.cc/u/lastchancename)\ **Post date:** [March 18, 2020, 11:10pm UTC](https://forum.arduino.cc/t/sim-7600-modem-no-voice-at-functionality/643147/5 "2020-03-18T23:10:12Z")
yep, thanks... that’s where I’ve started (and of course, wrote off to the shield manufacturer)... I have three pieces, one was a preproduction sample, and two more to work with until I finish the existing stock of (3G) 5320s... Thanks for the interest! ---
**Author:** ![lastchancename](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/lastchancename/32/215426_2.png) [@lastchancename](https://forum.arduino.cc/u/lastchancename)\ **Post date:** [March 19, 2020, 12:02am UTC](https://forum.arduino.cc/t/sim-7600-modem-no-voice-at-functionality/643147/6 "2020-03-19T00:02:00Z")
SOLVED Issue found was AT+CATR didn’t default properly even though it returned ‘0’ (all)... I explicitly set +CATR=1 (UART) and fixed the issue. Now all voice commands & messages etc come through the UART port as expected. ---
**Author:** ![Railroader](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/railroader/32/274550_2.png) [@Railroader](https://forum.arduino.cc/u/Railroader)\ **Post date:** [March 19, 2020, 12:21am UTC](https://forum.arduino.cc/t/sim-7600-modem-no-voice-at-functionality/643147/7 "2020-03-19T00:21:44Z")
Telling about a problem often makes people find the error. ---
**Author:** ![lastchancename](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/lastchancename/32/215426_2.png) [@lastchancename](https://forum.arduino.cc/u/lastchancename)\ **Post date:** [March 19, 2020, 12:49am UTC](https://forum.arduino.cc/t/sim-7600-modem-no-voice-at-functionality/643147/8 "2020-03-19T00:49:56Z")
Yeah, and expect the unexpected ! The doc declares the default correctly, the modem says it’s using the default, but the default doesn’t work. I should test to see if I set the default, whether it works then ! ---
**Author:** ![system](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/system/32/1140315_2.png) [@system](https://forum.arduino.cc/u/system)\ **Post date:** [May 5, 2021, 7:10pm UTC](https://forum.arduino.cc/t/sim-7600-modem-no-voice-at-functionality/643147/9 "2021-05-05T19:10:43Z")