CallHub Documentation

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Good Practices To Avoid Getting The Messages Filtered and Sender ID Blocked

There are various situations where the carriers filter the messages. Filtering may range based on how the messages were constructed to the number of messages sent per Caller ID in a certain amount of time. When the messages are filtered, the carrier marks the message as Spam and/or blocks the Sender ID. The following are the good practices to avoid getting your messages blocked and Sender ID filtered:

1. Do Not overwork a Single Long Phone Number

Sending high number of messages per Sender ID within short period of time may cause the number to be blocked or filtered by the carrier. In some countries like US, users can send 3600 messages per hour per Sender ID. If the 3600 messages were already sent out, the other messages will be marked as “Failed” and the Sender ID will be blocked. All future messages to be send out using the blocked Sender ID will get a “No Route” message status and the messages will not be delivered. CallHub platform takes care that we rate limit the messages to 1 message per second per sender ID.

2. Minimize the usage of Hyperlinks

Messages that are using hyperlinks are highly promotional especially bitly or any shortened links. The carriers detect and filter messages that are highly promotional and mark these messages as “Spam”. It is advisable to avoid or minimize the use of hyperlinks so that messages are not filtered.

3. Customize Your Message

Sending high number of identical messages are most likely to be filtered by the carrier. The carrier treats repeated identical messages as suspicious. When detected as Spam, the carrier will block the Sender ID used in sending the messages. In CallHub, you can customize your messages to send unique messages by adding Tags in your message. For example: {first_name}, {last_name}, and {poll_location}. CallHub system fetches the contact’s details and custom fields from the phonebook based on the tags and adds it to the message. Using this feature will make each messages sent as different and unique.

4. Split Phonebook

When sending large amount of messages using a long phone number, splitting contacts into different phonebook and run different campaigns may be a good idea. Sending messages using a different phone book reduces the amount of messages that is sent in a certain amount of time. It is advisable to run different campaigns for each phonebook after getting few replies as much as 20% before running the next campaign. This practice helps to control and manage the number of messages that is sent out to avoid getting filtered.

5. Use Adaptive Texting Block For Collective Calling

Adaptive Texting Block is a new feature implemented by CallHub. This is mainly used to improve outreach rate of the messages. This feature helps to detect Sender ID that is filtered and will automatically rent a new number from the same area code.

Another function of Adaptive Texting Block is handling local presence. It matches the region (state/capital/largest city) of the contacts. The rented numbers can also be easily managed since the rented numbers can be Paused or Start.

To learn more about Adaptive Texting Block, you can check out the quick guide here.

6. Use Short code

Short code is a 5 or 6 digits short numbers that can send and receive messages. When sending large amount of identical messages, the carriers in the country that is sending the messages to may require that this must be sent using a Short code. You can get as high as 100 messages/second outreach rate with Short codes.

CallHub offers Vanity and Regular short codes. Vanity short code costs $4,500 per 3 months and regular short code costs $3000 per 3 months. You can send a request through here.


The carriers doesn’t have standard practice on how the filtering works but following the good practices mentioned above can help you avoid getting the Messages filtered and Sender ID blocked. When avoided, this will save you time, work, money, and improve outreach rate.