diff --git a/nimble/transport/common/hci_h4/include/nimble/transport/hci_h4.h b/nimble/transport/common/hci_h4/include/nimble/transport/hci_h4.h
index 6ad083a05f..2378d658f8 100644
--- a/nimble/transport/common/hci_h4/include/nimble/transport/hci_h4.h
+++ b/nimble/transport/common/hci_h4/include/nimble/transport/hci_h4.h
@@ -43,8 +43,17 @@ struct hci_h4_allocators {
 extern const struct hci_h4_allocators hci_h4_allocs_from_ll;
 extern const struct hci_h4_allocators hci_h4_allocs_from_hs;
 
+/** Callback invoked on every frame that the H4 parser sees; it is this
+ *  callback's responsibility to dispatch packets to the transport layer.
+ */
 typedef int (hci_h4_frame_cb)(uint8_t pkt_type, void *data);
 
+/** Callback invoked at the start of every packet that the H4 parser sees,
+ *  to allow a transport to parse custom types of packets that the H4 parser
+ *  may not otherwise understand (for instance, TI eHCILL packets).
+ */
+typedef uint16_t(hci_h4_packet_cb)(const uint8_t *buf, uint16_t len);
+
 struct hci_h4_sm {
     uint8_t state;
     uint8_t pkt_type;
@@ -59,12 +68,19 @@ struct hci_h4_sm {
 
     const struct hci_h4_allocators *allocs;
     hci_h4_frame_cb *frame_cb;
+    hci_h4_packet_cb *packet_cb;
 };
 
 void hci_h4_sm_init(struct hci_h4_sm *h4sm,
                     const struct hci_h4_allocators *allocs,
                     hci_h4_frame_cb *frame_cb);
 
+/* We do not include this in sm_init to avoid breaking the API for other
+ * users, but ideally if you need to call this, you will call it immediately
+ * once, right after sm_init.
+ */
+void hci_h4_sm_set_packet_cb(struct hci_h4_sm *h4sm, hci_h4_packet_cb *packet_cb);
+
 int hci_h4_sm_rx(struct hci_h4_sm *h4sm, const uint8_t *buf, uint16_t len);
 
 #endif /* _HCI_H4_H_ */
diff --git a/nimble/transport/common/hci_h4/src/hci_h4.c b/nimble/transport/common/hci_h4/src/hci_h4.c
index fd89154a34..41a29c3f01 100644
--- a/nimble/transport/common/hci_h4/src/hci_h4.c
+++ b/nimble/transport/common/hci_h4/src/hci_h4.c
@@ -283,6 +283,15 @@ hci_h4_sm_rx(struct hci_h4_sm *h4sm, const uint8_t *buf, uint16_t len)
         rc = 0;
         switch (h4sm->state) {
         case HCI_H4_SM_W4_PKT_TYPE:
+            if (h4sm->packet_cb) {
+                /* perhaps the chipset / transport driver wants to inspect
+                 * start-of-packet and consume it on its own?  */
+                uint16_t consumed = h4sm->packet_cb(ib.buf, ib.len);
+                if (consumed) {
+                    hci_h4_ib_consume(&ib, consumed);
+                    continue;
+                }
+            }
             hci_h4_frame_start(h4sm, ib.buf[0]);
             hci_h4_ib_consume(&ib, 1);
             h4sm->state = HCI_H4_SM_W4_HEADER;
@@ -337,3 +346,9 @@ hci_h4_sm_init(struct hci_h4_sm *h4sm, const struct hci_h4_allocators *allocs,
     h4sm->allocs = allocs;
     h4sm->frame_cb = frame_cb;
 }
+
+void
+hci_h4_sm_set_packet_cb(struct hci_h4_sm *h4sm, hci_h4_packet_cb *packet_cb)
+{
+    h4sm->packet_cb = packet_cb;
+}