I received an email earlier from Voip.ms, with the following announcement. The feature makes a stonger case for wanting to move to pjsip: Today we officially launched our SMS through SIP feature. You can now send and receive SMS directly from your SIP softphone, device or PBX. Sending DID must have the "Short Message Service (SMS)" service option enabled. This option can be enabled from the Manage DIDs > Edit DID page. To send an SMS from your SIP account, it is required that you set your Caller ID number to one of your SMS enabled DIDs. This will be the number you will be sending the message from. You can configure the Caller ID number from your customer portal for the specific subaccount if you are using a softphone or directly from your extension or trunk if you are using an Asterisk or PBX server. It's important to note that if you configure your caller ID name in your SIP client to be a 10 digits number, this will override your caller ID number. If the caller ID name is anything different than a 10 digits number this will be discarded and the Caller ID number will be used. If you are an asterisk or PBX user, please make sure to use the latest version of Asterisk (v12 or higher) and use chan_pjsip for the trunk. This is an asterisk limitation. The Desktop version of Zoiper requires the user to have the PRO version activated to be able to send SMS messages as well as to enable SIP Presence. Please contact Technical Support to request SIP presence to be enabled for your account for the VoIP.ms POP you are using. While normally not required, there may be other cases not documented of softphones or apps requiring SIP Presence to be enabled. Please contact technical support if you encounter any issue with your specific software. The free Desktop version of Zoiper cannot send SMS messages and is only capable of receiving SMS. The mobile version of Zoiper is completely free of these limitations. Free version already works for sending and receiving without the need of SIP presence. Receiving DID must have the "Short Message Service (SMS)" service option enabled. This option can be enabled from the Manage DIDs > Edit DID page. Enable the option "SMS SIP Account" and select the account destination for your SMS messages to this number. The account receiving SMS must be registered successfully in any of our POPs. For SIP devices that require this information, such as a trunk or PBX, we encode the original destination number in a custom SIP header field named "X-SMS-To".