Superior app, ordered the sim card and received it in Operating problem. Only trouble is calls are delayed/drop out sometimes After i have complete bars. For somebody that doesn't have wifi and may't afford a cellphone Invoice I extremely suggest obtaining the sim card. SIP connects several different devices to https://techchronicle.net/exploring-the-world-of-text-messaging-providers-voip-api-cpaas-sip-trunking-and-twilio-byoc/