resources.conf: ec20: Enable voice support

It was tested that it could do MO and MT voicecall just fine as SierraW
modems.

Change-Id: Ie14c00f9f80e00fdbb52ab82a53b4b5a187d41e7
diff --git a/example/resources.conf.rnd b/example/resources.conf.rnd
index dd9dc8f..61c328e 100644
--- a/example/resources.conf.rnd
+++ b/example/resources.conf.rnd
@@ -87,7 +87,7 @@
   ki: 'BB70807226393CDBAC8DD3439FF54252'
   auth_algo: 'comp128v1'
   ciphers: [a5_0, a5_1]
-  features: ['sms', 'ussd', 'gprs', 'sim']
+  features: ['sms', 'voice', 'ussd', 'gprs', 'sim']
 
 - label: gobi2k
   path: '/sys/devices/pci0000:00/0000:00:12.2/usb1/1-1/1-1.5'