IMPORTANT! As of January 1, 2021, telephony options are available only to Bitrix24 commercial plan users. Please see Bitrix24 pricing page for current information.There are plenty of ways to contact existing and potential customers. Individual and bulk messaging in one of them. Thus, having a CRM system that is integrated with Twilio and other SMS sending services gives a number of advantages. Such a system is called Bitrix24.
* Please note that the information may have changed since the publication. For current prices and features please visit Bitrix24 pricing page.
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Bitrix24 CRM manual is available here. If you are interested in buying self-hosted editions of Bitrix24, which come with API, CMS and source code, can be easily customized and integrated with other tools, please download a trial version here.