If you are experiencing difficulty sending SMS messages to Verizon phones, it may be caused by a few different things depending on the method of delivery that you use. Some SMS / text messaging delivery methods are more reliable than others.
If you're using Verizon's SMTP-to-SMS gateways vtext.com or vwpix.com, those gateways have stringent anti-spam policies and also limit the amount of traffic that you are allowed to send in any given hour and on any given day.
Verizon's SMTP-to-SMS gateway respects SPF records and also checks for DKIM signatures in the mail header, so be sure your email domain and server's SPF records are up to date. If you are relaying the messages through an SMTP server, whether local or cloud based, you will also need to configure DKIM signatures as message traffic without a DKIM signature may be filtered as potential spam.
There is also a possibility that the volume of traffic you are sending may be too high for the gateway to allow it all to pass through successfully. If that is the case you will need to investigate another method of SMS delivery like cellular hardware or an SMS delivery service. The most reliable method of sending SMS messages uses cellular hardware (GSM modem or router). NotePage's PageGate text messaging software has integrated support for cellular hardware as well as all the standard sending protocols. When it is critical that messages are delivered this is a reliable option.
If you're using Verizon's EMAG platform and messages are failing, it could be a few things.
The most common issue is that Verizon's EMAG platform ties your API credentials to your public IP address. If your public IP address changes from what they have on file for you, your credentials will be rejected even if they are still valid.
To update the IP address, you will need to contact your EMAG representative and let them know what your new IP is. As soon as this is updated, your messages should start going through again!
Article Date: August 6, 2020