CRM Email & SMS Integration

I already run a custom CRM with 10 separate log-ins and now need messaging to live inside it instead of in external tabs. Here is what I’m after:

Email
• Each user must connect the CRM to their own Gmail account (OAuth preferred, no shared credentials) so they can compose, send, and read replies without ever leaving the system.
• I do want to capture the usual engagement metrics—opens and click-throughs—so please wire that into the send pipeline and surface the data on the contact’s timeline.

SMS
• The same convenience is required for text messages: users type a message in the record view, choose contacts, hit send, and replies appear in the same thread history. Messages have to go out from the individual’s own number/SIM, not a pooled short code.
• I haven’t locked in an SMS gateway yet, so bring your recommendation or outline what it will take to let a physical SIM (e.g., GSM modem) or a cloud gateway present the correct caller ID for each user.

Deliverables
1. Code or modules that plug into my existing CRM (PHP/Laravel) enabling per-user Gmail sync with open/click tracking.
2. Integrated SMS send/receive logic tied to each user’s number with clear setup docs.
3. Brief hand-off session and written instructions so my in-house dev can maintain credentials or swap gateways later.

If this sounds straightforward to you, let me know the approach, timeline, and any API limits I should anticipate.